Calculators

Math and everyday calculators

An ordinary week keeps producing numbers that will not resolve in your head. A form wants your age and the years-only answer feels imprecise. A scale and a tape measure give two figures but no verdict on the pairing. A price tag advertises thirty percent off and the arithmetic stalls at the till. A check arrives for a table of six and the shares refuse to come out even. And some questions are settled not by arithmetic at all but by chance — a draw that must be fair rather than merely quick. Each calculator on this page takes one of those questions and settles it.

The Age Calculator turns a birthdate into a precise statement — years, months, weeks, days, down to hours and minutes — for forms, birthdays, and milestones. The BMI Calculator converts a weight and height into one index, places it within the World Health Organization's weight categories, and shows the range considered healthy for your height; where those thresholds come from is set out in our editorial policy. The Percentage Calculator handles a share of a number, percentage increases and decreases, and what a change between two values is actually worth. At the till, the Discount Calculator prices a sale honestly — the price after one cut, the original hiding behind an advertised sale price, and what stacking two discounts (20% and then 10%) is really worth — while the Tip Calculator carries the same care to the restaurant check, tipping on the base you choose and splitting the total with the rounding difference shown rather than buried. The Random Number Generator settles the chance thread: integers across any range, decimal values, unique draws for a lottery-style raffle, and dice from d4 to d20, all drawn from the browser's cryptographic random source through a sampler that gives every value exactly equal weight.

Pick the one that matches the question in front of you.

Every tool below runs entirely in your browser — no signup, no downloads, no data leaves your device.