Calculators that show
their work.
Percentages, unit conversions, mortgage math, BMI. Every result includes the formula so you can check it yourself.
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All categories
Tools for money, health, math, and every unit conversion you'll run into.
Calculators
Academic
GPA, grade, final grade, SAT, ACT score calculators
Finance
Mortgage, loan, interest, retirement, ROI, savings calculators
Marketing
CPC, CPM, CTR, ROAS, CPA, LTV marketing calculators
Business
Margin, markup, break-even, commission, discount calculators
Health & Fitness
BMI, calorie, body fat, macro, TDEE, sleep, BAC calculators
Math
Percentage, fraction, average, rounding, and statistics calculators
Construction
Concrete, roofing, drywall, fencing, flooring, mulch calculators
Date & Time
Days between dates, age calculator, time duration tools
Fun & Utility
Tip calculator, fuel cost, electricity cost, unit price tools
Unit conversions
Length & Distance
Inches to cm, miles to km, feet to meters converters
Weight & Mass
Pounds to kg, ounces to grams, stones to kg converters
Temperature
Fahrenheit to Celsius, Celsius to Kelvin converters
Volume & Cooking
Teaspoons to tablespoons, cups to ml, oz to cups converters
Area
Square feet to square meters, acres to hectares converters
Speed
MPH to KPH, knots to mph speed converters
Frequency
Hz to kHz, MHz to GHz, RPM frequency converters
Methodology
Why we show the formula
Most calculator sites give you a number and that's it. We think you should see how the answer was calculated, so you can sanity-check it and learn the math for next time. Every result includes the formula, every page cites its sources, and nothing runs on a server you can't see.
Read the full methodology