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Work out your full monthly mortgage payment — principal, interest, tax, insurance and PMI — with a complete amortisation schedule and payoff date.

Solve any percentage question — what is X% of Y, X is what percent of Y, X is Y% of what, and percentage increases or decreases.

Calculate body mass index in metric or imperial units — WHO categories for adults, or CDC growth-chart percentiles for children and teens aged 2–19.

Find the monthly payment, total interest and full repayment schedule for any fixed-rate loan — personal, car, student or business.

Find your exact age in years, months and days — plus your age in weeks, hours, minutes and seconds, and how long until your next birthday.

See how savings grow with compound interest, with or without regular deposits, and how much of the total is interest rather than your own money.

Convert pay between hourly, daily, weekly, monthly and annual — accounting for holiday, so the hourly figure reflects what you actually work.

Calculate profit margin from cost and price, or work backwards to the price you need to hit a target margin. Shows markup alongside it.

Calculate sample or population standard deviation and variance, with every intermediate step shown and the choice of divisor explained.

Format, minify, validate and sort JSON entirely in your browser. Precise error messages with line and column, and nothing is ever uploaded.

Convert between metres, feet, inches, miles, kilometres and every other common unit of length.

Calculate your grade point average from letter grades and credit hours, on a 4.0 scale, with an optional prior GPA to get your cumulative average.