The “quick sums” of everyday life, for free. In your browser alone.

Free everyday calculators that work entirely in your browser

The calculators cover the sums that come up in everyday life, all completed in your web browser: the number of days between two dates, age from a date of birth, sales tax switching between tax-excluded and tax-included prices, discounts at a given percentage off, unit conversion for length, weight, area and temperature, BMI from height and weight, an estimated monthly income from an hourly wage, loan repayments on an equal principal-and-interest schedule, and even a timer and a stopwatch. No account and no app installation required: open one and start typing.

Each tool states its formula and criteria — BMI uses the Japan Society for the Study of Obesity thresholds, and loans use the equal principal-and-interest formula — so you can check the reasoning behind every result. All calculations run inside your browser (client-side), so the numbers you enter are never sent to a server. Closing the page clears them from your browser’s memory as well.