Unit converter. Convert anything, instantly.

Most conversion tools answer one question at a time: pick a unit, pick a second one, read a single number, start again. This unit converter calculator answers all of them at once. Type a value into any category and every unit in it fills in together — a length arrives as millimetres, centimetres, metres, kilometres, inches, feet, yards, miles and nautical miles in one glance, so you never have to know which output you wanted before you asked for it. Across 64 categories and 602 units, that is the whole idea: one input, and the complete unit conversion table sitting beside it.

Length, area, weight and temperature

The length pages cover the lookups people actually type — feet to meter, inch to mm, cm to inches, km to miles — and every common pair has a page of its own with a table of round values, so 1 through 1000 feet in metres is already written down before you arrive. Area works the same way: square feet, square metres, square yards, acres and hectares sit side by side, which is what a land unit converter is usually being asked to do. Weight moves between grams, kilograms, pounds, ounces, stones and tonnes. Temperature unit conversion handles Celsius, Fahrenheit and Kelvin as the offset scales they really are — their zero points are in different places, so a single multiplier would be quietly wrong, and each value is converted through kelvin as an absolute reference instead.

Pressure, torque, energy and electricity

Pressure unit conversion covers pascals, bars, psi, atmospheres, torr and millimetres of mercury. The torque unit converter covers newton-metres, pound-feet and kilogram-force metres. Energy covers joules, calories, BTU and kilowatt-hours; power covers watts, kilowatts and horsepower. Those last two are where the electricity questions land: a billed “unit” of electricity is one kilowatt-hour, so converting kWh to units is a one-to-one reading. What genuinely needs converting is power into energy, and that needs a duration — a 2 kW appliance run for three hours uses six units. The watt and kilowatt figures come from the power converter, the kWh from the energy one.

Metric and SI unit conversion you can check

Every unit here is stored as its relationship to the SI base unit for its category, so metric unit conversion and SI unit conversion are the model the whole site runs on rather than a mode you switch into. Each category page prints the full unit conversion table it converts with — every unit, its symbol, and its exact value in the base unit — so an answer can be checked instead of trusted. The factors themselves are written as their published definitions rather than as decimals copied from elsewhere: a mile is 1609.344 metres, because a typo in a definition is visible and a typo in a long decimal is not.

How to use it

Type a number into the value box and choose the unit it is in; everything else updates as you type. The “Precision & format” panel sets significant figures, switches to scientific notation, and turns imperial results into fractions. Press Ctrl+K — ⌘+K on a Mac, or just / — to jump to any category without leaving the keyboard, and the calculator beside the heading hands its result straight to the converter when a value has to be worked out first. The address bar tracks the value, the unit and the precision, so a copied link reopens exactly what you were looking at.

Free, private, and working offline

There is no account, no advertising, no usage limit and nothing to install. A search engine’s own conversion box answers one pair, needs a connection, and stops at the popular categories; this online unit converter also covers viscosity, luminance, radioactivity, magnetic flux, thermal conductivity, data transfer and number bases, and keeps the entire result set on screen while you work. Conversions are computed in your browser, so the values you type are never sent anywhere — the only thing stored on your device is your light or dark theme preference. Every page is a complete, correct conversion table before a single line of JavaScript runs, and any page you have opened once keeps working with no connection at all.

Looking for a single conversion? Every common pair — feet to meters, inches to mm — has a page of its own with a table of round values, linked from its category above.