Calculator for Operations
59 calculator tools hand-picked for Operations.
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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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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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Belt Pulley Speed Calculator
Driven speed N2 = N1 × D1 / D2, solve any unknown, plus belt speed and drive ratio, browser-only
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Board Foot Calculator
Thickness × width × length ÷ 12 = board feet — multi-row cut list, per-BF cost, imperial ⇄ m³ — browser-only
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Air Conditioner BTU Calculator
Room area × ceiling × orientation × people → cooling BTU/h, 匹 (horsepower) and kW — sizes an AC right the first time — 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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Carpet Calculator
Rooms + roll width + waste → linear metres, billed area (m² / ft² / sq yard) and cost — browser-only
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CNC Feeds and Speeds Calculator
Spindle RPM + feed rate from tool diameter, cutting speed, flutes and chip load — imperial ⇄ metric, material reference, one-click copy — browser-only
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Compression Ratio Calculator
Static compression ratio from swept + clearance volume, or from bore, stroke, chamber, dome and gasket — cc or ci — browser-only
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Concrete Calculator
Slab, column, round footing & stairs → cubic meters/yards + cement bags, sand and gravel — 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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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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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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Drywall Calculator
Wall + ceiling area → sheets, drywall screws, joint tape & compound — metric and imperial — browser-only
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EV Charging Cost Calculator
Battery kWh + charge % + tariff → cost per charge, per 100km/mile, and how much you save vs petrol — browser-only
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Fence Calculator
Total run + post spacing → posts, panels/pickets, rails, concrete bags — metric & imperial — browser-only
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Firewood Cord Calculator
Measure your wood pile, get cords + face cords, compare price per cord — feet ⇄ metres, one-click copy, browser-only
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Fiscal Year Calculator
Pick a date and a fiscal-year start month — get the FY label, quarter, day count and exact start/end dates, browser-only
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Flooring Calculator
Room sizes + flooring type + box coverage + waste → net area, boxes, planks, and cost — metric or imperial, browser-only.
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Freelance Hourly Rate Calculator
Back into the hourly rate you must charge from your target salary, business expenses, billable hours, profit margin, and taxes — 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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Gear Ratio Calculator
Gear & transmission ratio plus bicycle gear inches, development and speed from cadence — exact, browser-only
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Grass Seed Calculator
Lawn area + species + new/overseed → exact seed weight and bag count — metric & US — browser-only
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Gravel Calculator
Area + depth → volume, tonnes, bulk bags — driveways, drainage, paths — browser-only
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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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Insulation R-Value Calculator
Stack wall and roof layers, get total R-value, U-value and metric RSI — glass wool, foam board, wood and more — browser-only
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Inventory Turnover Calculator
COGS ÷ average inventory = turnover ratio, plus days sales of inventory (DSI) — type the average directly or let beginning + ending fill it in — browser-only
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ISO Date Deduplicator
Find duplicates and keep one clean copy of iso dates from pasted text or uploaded local files.
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ISO Date Extractor
Extract, dedupe, and export iso dates from pasted text or uploaded local files.
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ISO Date List Converter
Convert iso dates from pasted text or uploaded local files.
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ISO Date List Validator
Validate and explain issues in iso dates from pasted text or uploaded local files.
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ISO Date Normalizer
Normalize, sort, and prepare iso dates from pasted text or uploaded local files.
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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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Linux Permission (chmod) Calculator
Linux permission (chmod) calculator — convert between octal (755), symbolic (rwxr-xr-x), and ls -l forms, with safety warnings.
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LLM Pricing Calculator
Estimate daily and monthly LLM spend from tokens, request volume, and editable model prices.
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MPG Calculator
Distance + fuel → MPG (US/UK), L/100km, km/L, all at once + cost per mile/km — browser-only
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Mulch Calculator
Garden bed area + spread depth → cubic yards, bags and bulk — multi-bed, metric/imperial — 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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Paint Calculator
Wall area → litres & cans of paint, with doors/windows deducted, coats and price — metric & US units, browser-only
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Paver Calculator
Area ÷ paver size, rounded up, +10% for cuts — pavers per ft²/m², total cost, ft+in or m+cm — browser-only
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Plant Spacing Calculator
Bed size + in-row & row spacing → exact plant count — square vs triangular layout — browser-only
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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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Roof Pitch Calculator
Convert roof pitch between rise-over-run, degrees and percent, plus the rafter multiplier and real rafter length — browser-only
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Roofing Calculator
Roof footprint + pitch → real sloped area, roofing squares, shingle bundles or sheets and underlayment rolls — metric & US, browser-only
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Square Footage Calculator
Add every room, get one total in ft² and m² at once — waste % + cost — browser-only
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Stair Calculator
Total rise + steps → rise/run, slope, Blondel comfort check + side-view diagram — metric & imperial, browser-only
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Stepper Motor Steps Calculator
Step angle + microstepping + transmission → steps/rev, steps/mm, steps for any travel — Marlin/Klipper config, browser-only
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Three-Phase Power Calculator
P = √3 · VL · IL · cosφ — active kW, apparent kVA, reactive kVAR and reverse line current — browser-only
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Tile Calculator
Room area + tile size + grout joint + waste → tiles, boxes, and cost — metric or imperial, browser-only.
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Time Duration Calculator
Hours between two times, add or subtract time, and add up a timesheet — decimal hours + pay — browser-only
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Unix Timestamp Converter
Unix timestamp ⇄ human date — seconds / milliseconds / ISO 8601 — UTC and local — 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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Timezone Meeting Planner
Plan meetings across timezones — see when everyone's working hours overlap.
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Tire Size Calculator
Decode 225/45R17 into diameter, sidewall, circumference & revs/km — then compare two tires for speedometer error and clearance change. Browser-only.
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Unit Converter
Convert between length, weight, temperature, area, volume, speed, time — instant, 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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Wallpaper Calculator
Wall size + roll spec + pattern repeat → strips per roll, total strips, rolls to buy — handles straight & half-drop match — browser-only
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Wheelchair Ramp Slope Calculator
Rise → ADA 1:12 ramp length, slope percent, angle and a pass/fail check — reverse mode too — 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.