Calculator for Student
197 calculator tools hand-picked for Student.
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24-Point Solver & Game
24-point solver and game — enter 4 numbers and get every solution instantly, or play random hands against the clock.
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A1C to Blood Glucose Calculator
A1C ⇄ estimated average glucose, both ways, mg/dL or mmol/L, with the ADA range — educational, browser-only
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Add Days to Date Calculator
Add or subtract days, weeks, months, and years from any date — plus a business-day mode that skips weekends. Runs entirely in your browser.
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Age Calculator
Calculate your exact age — years, months, days, hours. Compare two dates or count to a future date.
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Annulus Area Calculator
Area between two concentric circles — A = π(R² − r²), ring width, inner and outer circumference, solve backwards from area — browser-only
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Arithmetic Sequence Calculator
Arithmetic sequence calculator — nth term, sum of the first n terms, and the common difference from any two terms, all in your browser.
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Armstrong Number Checker
Test if a number equals the sum of its digits each raised to the digit count (153 = 1^3 + 5^3 + 3^3), with full breakdown and a range list. Browser-only.
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Atom Economy Calculator
product molar mass ÷ Σ reactant molar masses × 100 — green-chemistry atom efficiency, with how it differs from percent yield — browser-only
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Blood Alcohol Content (BAC) Calculator
Widmark-formula BAC estimate from drinks, body weight, sex and time — educational only, never a fit-to-drive verdict — browser-only
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Number Base Converter
Number base converter — binary, octal, decimal, hex, and any base 2-36. Bitwise too.
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BaZi (Four Pillars) Calculator
BaZi (Four Pillars) calculator — Chinese metaphysics birth chart with 8 characters, five elements analysis.
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Binary Calculator
Add, subtract, multiply and divide two binary numbers, exact BigInt math, results in binary, decimal, hex and octal, browser-only
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Binomial Expansion Calculator
Expand (a + b)ⁿ term by term with exact BigInt coefficients, substitute numbers like (2x + 3)⁴, and pull out any single term — browser-only
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Birthday Paradox Calculator
Birthday paradox calculator — see the probability of shared birthdays in a group of N people, visualized step by step.
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Blood Pressure Category Checker
Enter systolic and diastolic, see your AHA category on a color scale — Normal to Crisis, education only, runs in your browser
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BMI Calculator
Body Mass Index calculator with WHO + Asian classifications — metric and imperial — browser-only
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BMR Calculator
BMR calculator — basal metabolic rate by Mifflin-St Jeor and Harris-Benedict (compared side-by-side).
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Body Fat Calculator
Body fat % calculator — 4 formulas (US Navy / BMI-based / YMCA / Jackson-Pollock) with body shape visualization.
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Body Surface Area (BSA) Calculator
Four formulas side by side — Mosteller, DuBois, Haycock, Gehan-George — cm/kg or in/lb, one-click copy, browser-only
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BPM Tap Counter
BPM tap counter — tap the spacebar to the beat, instantly get tempo with running average, find your song's tempo for DJ / dance / metronome.
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Buoyancy Force Calculator
F = ρ·V·g · Archimedes' principle · will it float or sink · fresh/sea water + air presets · apparent weight · 100% browser-only
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Caffeine Calculator
Track how much caffeine is still in your system, how much is left at bedtime, and when it drops to a sleep-friendly level — half-life model, browser-only.
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Calorie Calculator
Calorie calculator — daily calorie needs (BMR + TDEE), weight loss/gain targets, macro breakdown.
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Calorie Deficit Calculator
Pick a daily calorie deficit, enter your current and goal weight, and see how many weeks it takes and the date you'd hit your target — with a safety check, browser-only
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Calories Burned Calculator
MET-based calorie burn for 30+ activities — running, cycling, swimming, HIIT, housework — stack and total — browser-only
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Centripetal Force Calculator
Solve F = m·v²/r for force, mass, speed or radius, with angular speed ω and centripetal acceleration, browser-only
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Chemistry Equation Balancer
Chemistry equation balancer — paste an unbalanced equation, solve coefficients using the matrix method, show step-by-step.
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Chinese Numeric Converter
Arabic ⇄ Chinese number — simple (一二三), formal (壹貳參), or amount (金额大写 with 元角分).
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Chinese Stroke Counter
Chinese character stroke counter — count strokes for any hanzi, traditional or simplified.
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Chinese Zodiac Sign Checker (Sheng Xiao)
Chinese zodiac checker — your animal sign, element, compatibility, lucky numbers/colors by birth year.
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Circle Calculator
Know any one of radius, diameter, circumference or area, get the other three, plus arc length and sector area, browser-only
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College Major Matcher (Holland RIASEC, 40 Questions)
College major matcher — Holland code (RIASEC) test, 40 questions, recommend 10+ matching majors with career path.
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Color Mixer
Color mixer — blend any two colors with adjustable ratio, RGB/HSL/LAB color space, predict the result and copy hex.
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Permutation & Combination Calculator
nPr, nCr, n!, n^r and combinations-with-repetition — exact BigInt results with the formula and worked steps — browser-only
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Combined Gas Law Calculator
P1V1/T1 = P2V2/T2 solver, find any one of the six gas quantities, with Boyle, Charles and Gay-Lussac special cases, browser-only
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Completing the Square Calculator
Turn ax² + bx + c into vertex form a(x − h)² + k with every step shown — vertex, axis of symmetry, min/max, and solved by completing the square — browser-only
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Complex Number Calculator
Complex number calculator — +-×÷ + conjugate + modulus + argument + polar/Cartesian conversion + powers + roots + Euler form, complex plane visualization.
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Compound Interest Calculator
Compound interest calculator — see how money grows over time, with monthly contributions, charts, and breakdown.
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Cone Calculator
Radius + height of a right circular cone, instant volume ⅓πr²h, slant height, lateral and total surface area, plus reverse-solve, browser-only
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Confidence Interval Calculator
Mean and proportion confidence intervals with margin of error, exact z critical values, one-click copy, browser-only
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Western Zodiac Calculator (Sun Sign)
Western zodiac calculator — your sign, element, ruling planet, compatibility, daily traits.
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Continued Fraction Calculator
Expand a decimal or fraction into a continued fraction [a0;a1,a2,...] with the convergents that best approximate it — browser-only
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Cooking Unit Converter
Cooking unit converter — tsp / tbsp / cup / oz / ml / g for 100+ common ingredients with density.
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Coordinate Distance Calculator
Great-circle distance between two lat/long points with the Haversine formula, plus bearing and midpoint, all in your browser
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Correlation Coefficient Calculator
Paste X,Y pairs → Pearson r, r², covariance, regression line and a scatter plot — runs entirely in your browser
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Coulomb's Law Calculator
F = k·q1·q2 / r² — solve electrostatic force, distance or charge, signed result, µC/nC units, scientific notation — browser-only
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Countdown Timer
Countdown timer — to any date and event, with live ticking down to seconds.
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Cylinder Calculator
Volume, surface area and capacity of a cylinder from radius or diameter and height — reverse-solve for height, see litres of water — browser-only
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Date Difference Calculator
Days / weeks / months / years between two dates — plus business-days mode — browser-only
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Day of the Week Calculator
Type any date and read the weekday back — works for 1066, 1900 or 3000, with day-of-year, ISO week and days-from-today
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Days Until Date Calculator
How many days until a date — plus weeks, months, business days, exact remaining, and the weekday it lands on
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Decibel Calculator
Add sound levels, convert ratio ⇄ dB (power 10·log, amplitude 20·log), and read a common-sound reference table — browser-only
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Density Calculator
Solve ρ = m / V for density, mass, or volume · mixed units (g, kg, lb, mL, L, cm³, gallon) · 20 substance presets · floats-or-sinks verdict — all browser-only
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Derangement Calculator
Subfactorial !n — the number of permutations where nothing stays in its own place, exact via BigInt, with the 1/e probability — browser-only
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Derivative Calculator (Step-by-Step)
Derivative calculator with step-by-step — symbolic differentiation, chain/product/quotient rule shown, plot f(x) and f'(x).
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Dew Point Calculator
Air temperature + relative humidity to the exact dew point, with a comfort band — Magnus formula, reversible, browser-only
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Dice Probability Calculator
Exact odds for any NdS roll: full sum distribution, expected value, and P(sum = / ≥ / ≤ X), counted not simulated
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Dilution Calculator
Solve C1V1 = C2V2 and ratio dilutions (1:10) — stock + water amounts in mL / L / fl oz / gal — browser-only
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Divisors Calculator
List every factor of a number — divisor count, sum of divisors, factor pairs, prime and perfect-number check — runs in your browser
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Double Factorial Calculator
Exact n!! computed on BigInt — the full expansion (7!! = 7×5×3×1 = 105), odd or even chain, and the bridge to the ordinary factorial, all in your browser
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Egyptian Fraction Calculator
Turn any proper fraction into a sum of distinct unit fractions with the Fibonacci-Sylvester greedy algorithm, with the steps shown, browser-only
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Electricity Cost Calculator
Power × hours × tariff → kWh and cost per day, month, and year — add multiple appliances, account for standby — browser-only.
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Engineering Notation Converter
Plain number ⇄ engineering notation (×10³ⁿ) ⇄ SI prefix (47kΩ) — exponent always a multiple of 3, with scientific notation for contrast — browser-only
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Escape Velocity Calculator
v = √(2GM/r) — escape + orbital velocity for any planet, moon or star, in m/s, km/s and mph — browser-only
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Expected Value Calculator
E[X] = Σ x·p — enter outcomes and probabilities, get expected value, variance and standard deviation, all in your browser
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Expense Tracker
Expense tracker — log spend, categorize, see monthly totals, all in your browser.
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Final Grade Calculator
Current grade + final weight + target → exactly what you need on the final — browser-only
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Fish Tank Calculator
Fish tank size calculator — input fish species and count, get the minimum tank gallons/liters needed and stocking density warnings.
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Fraction Calculator
Add, subtract, multiply, divide fractions — auto-reduced, with steps, mixed ⇄ improper ⇄ decimal — browser-only
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Free Fall Calculator
h = ½gt² · v = √(2gh) · solve from height, time, or impact speed · Earth, Moon, Mars gravity · browser-only
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Frequency Wavelength Calculator
Convert frequency to wavelength and back with λ = v/f, pick the wave speed, read the EM spectrum band, copy in one click, browser-only
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Frustum Volume Calculator
Conical frustum (truncated cone) volume, slant height, lateral and total surface area from R1, R2 and h — browser-only, one-click copy
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Fuel Cost Calculator
Trip fuel cost from distance + economy + price — round trip, per-person split, L/100km ⇄ MPG — browser-only.
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Future Value Calculator
Project the future value of a lump sum plus regular contributions — full time-value-of-money math, year-by-year, browser-only
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2048 Game (Slide, Merge, Reach 2048)
2048 game — slide tiles, combine numbers, reach 2048. Pure browser, no ads, your high score saved locally.
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GC Content Calculator
Paste a DNA or RNA sequence and get GC%, AT%, per-base counts, length and a melting-temperature estimate. FASTA headers and spaces are ignored, invalid bases flagged, all in your browser.
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GCD & LCM Calculator
GCD + LCM of any list of integers — Euclidean steps, prime factorization, prime-factor table — exact BigInt math, browser-only
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Gear Ratio Calculator
Gear & transmission ratio plus bicycle gear inches, development and speed from cadence — exact, browser-only
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Geometric Sequence Calculator
Geometric sequence calculator — nth term, sum of first n terms, and infinite series sum from first term a and common ratio r, all in your browser.
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GPA Calculator
Weighted GPA from courses + credits + grades — US 4.0 / 4.3 and China 4.0 / 4.5 conversion, letter ⇄ percentage ⇄ point — browser-only
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Grade Calculator
Weighted course grade + what you need on the final — multi-row categories, letter grade, shareable link — browser-only
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Gravitational Force Calculator
F = G·m1·m2 / r² · solve for force, distance or mass · scientific notation · Earth/Moon/Sun presets · 100% browser-only
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Half-Life Calculator
Solve any radioactive-decay unknown — initial amount, remaining amount, elapsed time, or half-life — with exact exponential math, all in your browser
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Happy Number Checker
Replace N with the sum of its squared digits — reach 1 and it is happy, hit the 4-cycle and it is not. See every step.
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Heart Rate Zones Calculator
Heart rate zones calculator — max HR (4 formulas) + 5 training zones (recovery/aerobic/tempo/threshold/VO2max), with workout examples.
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Heat Index Calculator
Air temperature + humidity to the real "feels-like" temperature, with NWS risk level — exact Rothfusz regression, browser-only
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Henderson-Hasselbalch Calculator
Buffer pH = pKa + log([A⁻]/[HA]) — forward and reverse, acetate/phosphate/Tris/bicarbonate presets — browser-only
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Hooke's Law Calculator
F = k·x spring calculator: solve any one of force, spring constant or displacement from the other two, plus elastic potential energy ½kx² — browser-only
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Ideal Gas Law Calculator
Solve PV = nRT for pressure, volume, amount, or temperature — pick any unknown, mix any units, runs in your browser
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Ideal Weight Calculator
Devine + Robinson + Miller + Hamwi formulas, side by side, plus the healthy BMI weight band — metric and imperial — browser-only
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IELTS Band Calculator
IELTS band calculator — convert listening/reading raw scores to band, average four skills, see your overall band.
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Integral Calculator (Step-by-Step)
Indefinite integral calculator step-by-step — symbolic integration, substitution + integration by parts shown, plot f(x) and F(x).
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Intermittent Fasting Tracker — 16:8 / OMAD / 5:2 / 36h Timer with Stages
Intermittent fasting tracker — 16:8 / 18:6 / 20:4 / OMAD / 5:2 / 36h timer with stages and history log.
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Jet Lag Calculator
Estimate how many days jet lag will last and build a day-by-day plan to pre-shift your body clock before you fly — eastbound vs westbound, light and melatonin timing, all in your browser
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Julian Date Converter
Gregorian date ⇄ Julian Day Number (JDN), fractional JD, Modified Julian Date (MJD) and ordinal day-of-year — astronomy-grade, browser-only
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Kids Allowance Calculator
Kids allowance calculator — age-appropriate weekly/monthly amount with chore-based breakdown, savings goal sandbox.
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Kinetic Energy Calculator
KE = ½mv², solve for energy, mass or speed, with formula steps and momentum, all in your browser
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Lean Body Mass Calculator
Boer, James and Hume LBM side by side, plus fat mass and a direct body-fat path, metric or imperial, fully in your browser
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Leap Year Checker
Is it a leap year? Type any year for a yes/no, the 4/100/400 rule worked out, Feb length, and the next leap year, browser-only
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Lens Equation Calculator
Solve 1/f = 1/do + 1/di — enter any two of focal length, object and image distance, get the third plus magnification and a real/virtual verdict, browser-only
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Logarithm Calculator
log_b(x), ln, log₁₀, log₂ and antilog in one place — change-of-base steps shown, one-click copy, browser-only
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Lunar Calendar Converter (Chinese Nongli)
Gregorian ⇄ Chinese Lunar (Nongli) calendar — bi-directional, accurate 1900-2100.
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Macro Nutrient Calculator
Macro nutrient calculator — TDEE + protein/fat/carb split for cut/maintain/bulk goals, with 3 split presets (high-protein/keto/balanced) and meal example.
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Marathon Time Predictor
Marathon time predictor — input 5k/10k/half time, get full marathon prediction via 3 formulas (Riegel/Cameron/VDOT), with pace zones and weekly mileage advice.
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Math Formula Reference
Math formula reference — algebra, geometry, trigonometry, calculus, statistics, all in one place.
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Matrix Calculator
Matrix calculator — add/sub/multiply/inverse/determinant/transpose/rank/RREF/eigenvalues for n×m matrices, step-by-step.
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MBTI Quick Test (28 Questions, 16 Personality Types)
MBTI quick test — 28 questions, 5 minutes, get your 4-letter type with detailed reading.
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Modulo Calculator
a mod n in both conventions — the % your language returns AND the math mod that is never negative, plus floor quotient, modular power and inverse
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Molality Calculator
Molal concentration b = n / m — moles of solute per kilogram of solvent, solve any one of moles, solvent mass, or molality, or start from grams + molar mass, browser-only
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Molar Mass Calculator
Type any chemical formula — get molar mass, a per-element mass-percent table, and mass↔mole conversion. IUPAC weights, browser-only.
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Molarity Calculator
Molar concentration c = n / V — solve any one of moles, volume, concentration, or go straight from grams + molar mass — browser-only
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Moment of Inertia Calculator
Pick a shape, enter mass and size, read I in kg·m² — cylinder, sphere, rod, point mass, plus rotational KE — browser-only
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Momentum & Impulse Calculator
p = m·v and J = F·Δt = Δp — solve any one of momentum, mass, velocity, impulse, force or time, with kg·m/s, g, m/s and km/h units — browser-only
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Moon Phase Calculator
Pick any date, see the moon phase, illumination percentage and moon age, plus this month's principal phases, all in your browser
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Multinomial Coefficient Calculator
n! / (k1!·k2!·…) computed exactly with BigInt — ways to split n items into fixed-size groups, the multinomial-theorem term coefficient, browser-only
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Ohm's Law Calculator
Enter any two of voltage, current, resistance, or power — get the other two plus the formula used — with mV/V/kV, µA/mA/A, Ω/kΩ/MΩ, mW/W/kW prefixes — browser-only.
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One-Rep Max Calculator
Estimate your 1RM from any set with five formulas at once, then read a full %1RM training-load table — kg or lb, browser-only
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Orbital Period Calculator
T = 2π·√(a³ / GM) · Kepler's third law · solve period or semi-major axis · orbital speed · Sun/Earth/Jupiter presets · 100% browser-only
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Ovulation & Fertility Tracker
Ovulation & fertility tracker — predict next 6 months of fertile windows, track BBT, find best conception days.
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Pendulum Period Calculator
T = 2π√(L/g) — solve a simple pendulum's period, frequency or length, with Earth, Moon and Mars gravity, browser-only
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Percent Composition Calculator
Mass percent of every element in a compound — type a formula, read the breakdown — IUPAC atomic weights, browser-only
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Percent Error Calculator
Compare a measured value against the true value — get percent error, absolute error, relative error, and signed high/low. Plus a percent-difference mode for two trials with no accepted answer.
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Percent to Fraction Converter
Percent ⇄ fraction, both ways. 25% becomes 1/4, 3/4 becomes 75%, decimal percents and values over 100% included, fully reduced, browser-only.
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Percent Yield Calculator
actual ÷ theoretical × 100 — solve for percent, actual or theoretical yield, grams or moles, with a plain-English read on why it is below or above 100% — browser-only
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Percentage Calculator
5 common percentage calculations — "x% of y", "x is what% of y", percentage change, increase/decrease — instant, browser-only
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Percentage Change Calculator
Growth rate, drop, percentage-point gap, and reverse-solve the new value — signed, color-coded, browser-only
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Percentile Calculator
Any percentile P plus Q1 Q2 Q3, IQR, five-number summary, box plot and 1.5×IQR outliers, browser-only
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Periodic Table
Interactive periodic table — 118 elements, properties, electron config, search.
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Pet Age Calculator
Pet age calculator — accurate dog/cat human-age equivalent, with breed size adjustment, lifespan stages.
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Pet Food Calculator
Pet food calculator — RER + activity factor for dogs and cats, exact daily grams based on weight, age, neuter status, and kibble kcal/100g.
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pH Calculator
pH, pOH, [H+] and [OH-] from any one value, with an acid/base verdict and a 0-14 colour scale, all in your browser
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Photon Energy Calculator
Wavelength or frequency in, photon energy out in joules and eV — Planck equation E = hf = hc/λ, with EM band — browser-only
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Barbell Plate Calculator
Target weight → exactly which plates to slide on each end — kg & lb, with a live barbell diagram — browser-only
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Polar / Rectangular Coordinate Converter
Convert (x, y) to (r, θ) and back, degrees or radians, with a live coordinate diagram, browser-only
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Pomodoro Timer
Pomodoro timer — 25/5 classic, plus 50/10 and 90/15 long-focus modes, with sound, browser tab title, daily stats.
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Pool Volume Calculator
Find how many gallons (and liters and cubic meters) your pool holds — rectangle, round, oval, or sloped floor — in feet or meters
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Pregnancy Weight Gain Calculator
Pre-pregnancy BMI + week → IOM recommended total gain, the by-week target, and an on-track check — singleton & twins — browser-only
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Prime Number Calculator
Test primality · factorize · list primes in a range · find the N-th prime — exact BigInt math, browser-only
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Probability Distribution Visualizer
Probability distribution visualizer — normal/t/chi-sq/F/binomial/poisson/exp/uniform PDF+CDF, P(a≤X≤b) area, z/p table replacement.
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Projectile Motion Calculator
Solve flight time, max height, range & impact speed from launch speed, angle and height — with a live trajectory plot, browser-only
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Protein Intake Calculator
Protein intake calculator — daily grams by body weight, activity, goal (cut/maintain/bulk), per ISSN 2017 guidelines.
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Punnett Square Calculator
Cross two genotypes — Aa × Aa or AaBb × AaBb — get the grid, the genotype ratio and the phenotype ratio, one-click copy, browser-only
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Pythagorean Theorem Calculator
Solve a²+b²=c² — find the hypotenuse, find a missing leg, or measure the distance between two points (2D & 3D). Browser-only.
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Quadratic Equation Solver
Quadratic equation solver — ax² + bx + c = 0, discriminant analysis, real + complex roots, vertex/intercepts, parabola visualization.
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Random Number Generator
Generate cryptographically-secure random integers — single or batch, with/without duplicates — browser-only
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Ratio Calculator
Solve a:b = c:x, simplify ratios, split a total by a ratio, scale a recipe up or down — with full steps, browser-only
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Recipe Scaler
Recipe scaler — paste any recipe, change servings, get all ingredient amounts auto-scaled. Handles fractions and unit conversion.
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Regular Polygon Calculator
Sides n + side length s, get area, interior angle, apothem and both radii, with a to-scale n-gon drawn live, browser-only
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Resistor Color Code Calculator
Decode 4, 5 and 6-band resistors to Ω, tolerance and tempco — or go the other way, with a live color-band drawing
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Rocket Equation Delta-v Calculator
Tsiolkovsky Δv = ve·ln(m0/mf) — solve from exhaust velocity or specific impulse, reverse-solve propellant, mass ratio, browser-only
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Roman Numeral Converter
Arabic ⇄ Roman, both directions, live — strict validation, step-by-step breakdown, vinculum up to 3,999,999 — 100% browser-only
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Rule of 72 Calculator
Estimate doubling time from a rate (72 ÷ r), or the rate from a target time — side by side with the exact ln(2)/ln(1+r) figure — browser-only
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Running Pace Calculator
Running pace calculator — convert between pace / time / distance, predict 5K/10K/half/full marathon from one race.
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Safe Period & Ovulation Calculator
Period & ovulation calculator — predict next period, fertile window, safe days (based on calendar method).
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Sample Size Calculator
How many people to survey for a given confidence and margin of error — finite-population correction, reverse mode, one-click copy, browser-only
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Savings Goal Tracker
Savings goal tracker — set a target (down payment, trip, emergency fund), see weekly/monthly contribution and projected date.
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Schwarzschild Radius Calculator
R_s = 2GM/c² — turn any mass into its black-hole event horizon, in metres, km or light-seconds, with presets and inverse solve — browser-only
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Scientific Calculator
Scientific calculator — sin / cos / log / sqrt / power, with full keyboard input + history, deg/rad mode.
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Scientific Notation Converter
Plain ⇄ scientific (a×10ⁿ) ⇄ engineering ⇄ E-notation — with significant figures, exact big/small numbers — browser-only
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Screen Time Budget
Screen time budget — track and visualize daily screen time across phone/tablet/PC, with age-based recommendations from WHO/AAP.
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Chinese Zodiac Compatibility (Shengxiao Match)
Chinese zodiac compatibility — match two people by their zodiac signs, 144 pair combinations with reading.
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Significant Figures Calculator
Count sig figs · round to N significant figures · do sig-fig arithmetic — exact string-level math, browser-only
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Simple Interest Calculator
I = P × r × t — solve for interest, principal, rate, or time, plus total and a simple-vs-compound gap — browser-only
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Simplify Fraction Calculator
Reduce any fraction to lowest terms, see the GCD it divided by, and flip between improper and mixed forms, all in your browser
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Sleep Cycle Calculator
Sleep cycle calculator — 90-minute REM cycles. Find best bedtime if you must wake at X, or best wake time if you sleep at Y.
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Sleep Debt Calculator
Sleep debt calculator — track this week's sleep hours, see your accumulated debt, get a realistic recovery plan based on research.
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Slope Calculator
Two points in, full line out — slope, angle, distance, midpoint, y = mx + b and grade % — browser-only
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Snell's Law Calculator
n1·sin(θ1) = n2·sin(θ2) — solve refraction angle, critical angle and total internal reflection — browser-only
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Special Number Checker
Type one integer, see at a glance whether it is prime, perfect, abundant, deficient, triangular, square, cube, Fibonacci, palindrome, with the reason for each, browser-only
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Specific Heat Calculator
Q = m·c·ΔT — solve for any of heat, mass, specific heat or temperature change, with water/aluminum/iron/copper presets and J/kJ/cal units — browser-only
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Sphere Calculator
Type any one of radius, diameter, volume or surface area — the other three solve instantly, plus how many liters the ball holds — browser-only
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Stair Climbing Calorie Calculator
Stair climbing calorie calculator — calculate kcal burned by floors climbed, with METs-based formula.
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Statistics Basic Calculator
Basic statistics calculator — mean/median/mode/variance/std-dev/quartiles/range/IQR/skewness/kurtosis + histogram + box plot, paste any numbers.
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Stefan-Boltzmann Law Calculator
P = εσAT⁴ — radiated power, radiant exitance and the inverse (power → temperature), with Sun and body presets — browser-only
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Strength 1RM & Training Program
Strength 1RM calculator + training program — 6 formulas (Epley/Brzycki/Lombardi/O'Conner/Lander/Mayhew), %1RM table, Wendler 5/3/1 + Sheiko + Madcow templates.
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Sudoku Generator
Sudoku generator and solver — 4 difficulties (easy / medium / hard / expert), unique-solution guaranteed, play in the browser or print as PDF.
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TDEE Calculator
TDEE calculator — BMR × activity factor, with cut/bulk calorie targets and projected weekly weight change.
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Tempo Delay Calculator
Turn any BPM into a full delay-time table — milliseconds and Hz for every note value, plus dotted and triplet. Built for mixing and producing.
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Test Grade Calculator
Answers wrong → percent + letter grade + a full printable grading chart — the teacher's EZ Grader, browser-only
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Timezone Converter
Convert any time between any two timezones — DST-aware, IANA database — browser-only
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Triangle Calculator
Triangle solver — SSS, SAS, ASA, AAS, and the ambiguous SSA case via law of sines + law of cosines. All sides, angles, area, perimeter, type, drawn to scale.
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Trigonometry Calculator
Trigonometry calculator — sin/cos/tan + inverse + sec/csc/cot, degree/radian/gradient, unit circle visualization, exact values.
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Typing Speed Test
Typing speed test — WPM, accuracy, real-time mistakes, English + Chinese pinyin modes.
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Unit Converter
Convert between length, weight, temperature, area, volume, speed, time — instant, browser-only
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Vector Calculator
Add, subtract, scale, dot, cross, magnitude, angle, unit vector and projection for 2D and 3D vectors — browser-only
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VO₂max Calculator
Estimate your maximal oxygen uptake from four field tests — Cooper run, 1.5-mile, resting HR, Rockport walk — with a fitness grade by age and sex
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Waist-to-Height Ratio Calculator
WHtR = waist ÷ height, one number that flags abdominal fat better than BMI, with cm/in, sex-aware bands and one-click copy, browser-only
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Waist-to-Hip Ratio Calculator
WHR = waist ÷ hip, scored against the WHO health-risk bands by sex, with an optional waist-to-height check — runs entirely in your browser
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Water Intake Calculator
Water intake calculator — daily water target by body weight, activity, climate. With drink-log to track today's progress.
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Wavelength Frequency Calculator
Convert between wavelength λ, frequency f, and photon energy E · c = λf · E = hf · spectrum band + visible colour · browser-only
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Weight Loss Tracker & Calorie Deficit Calculator
Weight loss tracker — set target, log daily weight, see trend, project goal date with real calorie math.
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Weight Training Tracker — 1RM Calculator & Strength Progress Log
Weight training tracker — log compound lifts (squat/bench/deadlift/OHP), track 1RM via Epley formula, see strength gains by week.
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Weighted Average Calculator
Any value × weight pairs, weighted mean = Σ(value×weight)/Σweight, plus plain average and per-row contribution, browser-only
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Weighted Grade Calculator
Items + weights → your current course grade, with letter and banked points — browser-only
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Wind Chill Calculator
Turn air temperature and wind speed into a feels-like number — and a frostbite warning — using the official NWS / Environment Canada formula. Metric or imperial, browser-only.
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Work and Power Calculator
W = F·d·cosθ and P = W/t — solve work, power or force, with angle, P = F·v and HP ⇄ W — browser-only
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Z-Score Calculator
Standardize any value, reverse a z-score back to raw, or compute μ and σ from a dataset — with left/right/two-tailed normal probabilities and percentile