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Browse every free online calculator on OG Calculators by category. Math, finance, health and education calculators, all instant and free to use.

5 categories 36 calculators 100% Free No sign-up

Percentages, fractions, averages, ratios and full scientific expressions, each one worked out instantly with the method shown.

Area, volume, distance, slope and the right-angle maths behind real building work, with the formula and the working shown every time.

What a loan really costs, what savings grow to and whether buying beats renting, worked out with real amortisation rather than rough estimates.

BMI, daily calories, pregnancy dates and ovulation timing, worked out with the standard formulas and every assumption stated plainly.

Dates, grades, unit conversions, random draws and number-base conversions for the small jobs that come up every week.