Unit Converter

Unit converter — free, fast, and private

Converting between units of measurement comes up constantly — a recipe in millilitres, a road sign in miles, a parcel weight in pounds, a file size in gigabytes. This converter handles the common categories in one place: pick a category, enter a value, choose the units to convert from and to, and the answer appears instantly. Everything runs in your browser, so nothing you type is uploaded.

It recalculates live as you type and swaps direction with one tap, so you can go from kilometres to miles and back without re-entering anything. No sign-up, no app, and it works offline once the page has loaded.

What you can convert

The converter covers eight everyday categories:

• Length — metres, kilometres, centimetres, millimetres, miles, yards, feet, inches
• Weight / mass — kilograms, grams, milligrams, metric tonnes, pounds, ounces
• Temperature — Celsius, Fahrenheit, Kelvin
• Volume — litres, millilitres, and US gallons, quarts, pints, cups, and fluid ounces
• Area — square metres, square kilometres, square feet, acres, hectares
• Speed — km/h, mph, m/s, knots
• Time — seconds, minutes, hours, days
• Digital storage — bytes, KB, MB, GB, TB

How the conversions work

Most units convert by a simple ratio. Every unit in a category has a fixed relationship to a base unit — for length, everything is defined in terms of the metre — so converting means scaling through that base. One mile is 1,609.344 metres, so 1 mile is 1.60934 kilometres; one kilogram is 2.20462 pounds; one US gallon is 3.78541 litres. These factors are exact definitions, not approximations, so the results are as accurate as the rounding shown.

Results are trimmed to a sensible number of significant figures so you don't get a long tail of decimals, while exact whole numbers — like a megabyte being 1,048,576 bytes — are shown in full.

Temperature is different

Temperature is the one category that isn't a simple multiplication, because the scales don't share a zero point. Converting Celsius to Fahrenheit means multiplying by 9/5 and then adding 32, and Kelvin is Celsius shifted by 273.15 degrees. That offset is why 0°C is 32°F, not 0°F. The converter uses the proper formulas, so the familiar reference points all come out right: water freezes at 0°C = 32°F = 273.15 K and boils at 100°C = 212°F = 373.15 K, and the point where the two scales meet, −40°C = −40°F, checks out too. Negative temperatures are fully supported.

Binary vs decimal storage units

Digital storage has a well-known ambiguity. This tool uses binaryunits, where 1 KB = 1,024 bytes, 1 MB = 1,024 KB, and so on — which is how operating systems usually report file and drive sizes. Under the strict international (SI) standard, the prefixes kilo, mega, and giga mean powers of 1,000, and the powers-of-1,024 units are written KiB, MiB, and GiB. Drive manufacturers often advertise using the 1,000 convention, which is part of why a "1 TB" drive can look smaller once your computer reports it in binary terms. If you specifically need the decimal (1,000) interpretation, keep that difference in mind when reading the result.

US customary volume units

The volume category uses US customary units for gallons, quarts, pints, cups, and fluid ounces. These differ from the UK (imperial) versions — a US gallon is about 3.785 litres while an imperial gallon is about 4.546 litres, and US and imperial fluid ounces differ slightly too. If you're working from a British recipe or spec, that distinction matters, so it's worth confirming which system your source uses.

Works on your phone

The converter is built mobile-first. The category and unit selectors use the native picker, so on a phone you get the familiar scrolling list, and the value field opens the numeric keypad. The swap button is a large, thumb-friendly target, and the result updates instantly right on screen. Because everything is computed locally, there's no waiting on a network.

Privacy: your numbers never leave your device

Every value you enter is used only to do the conversion in your browser. Nothing is uploaded, nothing is stored on a server, and there is no account to create. When you close the page the numbers are gone, because they were never sent anywhere in the first place.

Frequently asked questions

Which units can I convert?

Length, weight and mass, temperature, volume, area, speed, time, and digital storage — pick a category and the matching units appear for both sides of the conversion.

Are the conversions accurate?

Yes. The factors are exact standard definitions (for example, 1 inch = 25.4 mm and 1 pound = 453.59237 g), and temperature uses the proper non-linear formulas. Results are rounded for readability, not because the underlying math is approximate.

Do you use binary or decimal for storage?

Binary: 1 KB = 1,024 bytes, 1 MB = 1,024 KB, and so on, which matches how most operating systems report sizes. The strict SI standard uses 1,000 and writes 1,024-based units as KiB, MiB, GiB.

Is my data uploaded to a server?

No. Everything runs in your browser — the numbers you enter never leave your device, and nothing is stored or sent anywhere.