Calculator for Operations

45 calculator tools hand-picked for Operations.

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.
Board Foot Calculator

Thickness × width × length ÷ 12 = board feet — multi-row cut list, per-BF cost, imperial ⇄ m³ — browser-only
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.
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.
Carpet Calculator

Rooms + roll width + waste → linear metres, billed area (m² / ft² / sq yard) and cost — browser-only
Concrete Calculator

Slab, column, round footing & stairs → cubic meters/yards + cement bags, sand and gravel — browser-only
Date Difference Calculator

Days / weeks / months / years between two dates — plus business-days mode — browser-only
Days Until Date Calculator

How many days until a date — plus weeks, months, business days, exact remaining, and the weekday it lands on
Dilution Calculator

Solve C1V1 = C2V2 and ratio dilutions (1:10) — stock + water amounts in mL / L / fl oz / gal — browser-only
Drywall Calculator

Wall + ceiling area → sheets, drywall screws, joint tape & compound — metric and imperial — browser-only
EV Charging Cost Calculator

Battery kWh + charge % + tariff → cost per charge, per 100km/mile, and how much you save vs petrol — browser-only
Fence Calculator

Total run + post spacing → posts, panels/pickets, rails, concrete bags — metric & imperial — browser-only
Flooring Calculator

Room sizes + flooring type + box coverage + waste → net area, boxes, planks, and cost — metric or imperial, browser-only.
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
Gear Ratio Calculator

Gear & transmission ratio plus bicycle gear inches, development and speed from cadence — exact, browser-only
Grass Seed Calculator

Lawn area + species + new/overseed → exact seed weight and bag count — metric & US — browser-only
Gravel Calculator

Area + depth → volume, tonnes, bulk bags — driveways, drainage, paths — browser-only
Heat Index Calculator

Air temperature + humidity to the real "feels-like" temperature, with NWS risk level — exact Rothfusz regression, browser-only
ISO Date Deduplicator

Find duplicates and keep one clean copy of iso dates from pasted text or uploaded local files.
ISO Date Extractor

Extract, dedupe, and export iso dates from pasted text or uploaded local files.
ISO Date List Converter

Convert iso dates from pasted text or uploaded local files.
ISO Date List Validator

Validate and explain issues in iso dates from pasted text or uploaded local files.
ISO Date Normalizer

Normalize, sort, and prepare iso dates from pasted text or uploaded local files.
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
Linux Permission (chmod) Calculator

Linux permission (chmod) calculator — convert between octal (755), symbolic (rwxr-xr-x), and ls -l forms, with safety warnings.
LLM Pricing Calculator

Estimate daily and monthly LLM spend from tokens, request volume, and editable model prices.
MPG Calculator

Distance + fuel → MPG (US/UK), L/100km, km/L, all at once + cost per mile/km — browser-only
Mulch Calculator

Garden bed area + spread depth → cubic yards, bags and bulk — multi-bed, metric/imperial — browser-only
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
Paint Calculator

Wall area → litres & cans of paint, with doors/windows deducted, coats and price — metric & US units, browser-only
Plant Spacing Calculator

Bed size + in-row & row spacing → exact plant count — square vs triangular layout — browser-only
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
Roofing Calculator

Roof footprint + pitch → real sloped area, roofing squares, shingle bundles or sheets and underlayment rolls — metric & US, browser-only
Square Footage Calculator

Add every room, get one total in ft² and m² at once — waste % + cost — browser-only
Stair Calculator

Total rise + steps → rise/run, slope, Blondel comfort check + side-view diagram — metric & imperial, browser-only
Tile Calculator

Room area + tile size + grout joint + waste → tiles, boxes, and cost — metric or imperial, browser-only.
Time Duration Calculator

Hours between two times, add or subtract time, and add up a timesheet — decimal hours + pay — browser-only
Unix Timestamp Converter

Unix timestamp ⇄ human date — seconds / milliseconds / ISO 8601 — UTC and local — browser-only
Timezone Converter

Convert any time between any two timezones — DST-aware, IANA database — browser-only
Timezone Meeting Planner

Plan meetings across timezones — see when everyone's working hours overlap.
Tire Size Calculator

Decode 225/45R17 into diameter, sidewall, circumference & revs/km — then compare two tires for speedometer error and clearance change. Browser-only.
Unit Converter

Convert between length, weight, temperature, area, volume, speed, time — instant, browser-only
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
Wallpaper Calculator

Wall size + roll spec + pattern repeat → strips per roll, total strips, rolls to buy — handles straight & half-drop match — browser-only
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.