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
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