Unit converter
Runs entirely in your browser. Your files and data never leave your device.
| mm | 1,000 | |
|---|---|---|
| cm | 100 | |
| m | 1 | |
| km | 0.001 | |
| in | 39.37007874 | |
| ft | 3.280839895 | |
| yd | 1.093613298 | |
| mi | 0.0006213711922 | |
| nmi | 0.0005399568035 |
About this tool
This tool converts a value from one unit to another and also shows it in every other unit in the same category at once. Pick a category such as length or temperature, choose the units you’re converting between, and type a number to see the result plus a full table for reference.
Which categories and units does it cover?
Length, mass, area, volume, speed, pressure, energy, power, angle, and temperature, each with a handful of common units: length spans millimeters through miles and nautical miles, volume covers metric units alongside US cooking measures like cups and tablespoons, and pressure includes pascals, bar, atmospheres, psi, and mmHg. Every category except temperature converts by a straightforward multiplication through a shared base unit (meters for length, liters for volume, and so on), which is also why the tool can show the full comparison table for free: once a value is converted to the base unit, every other unit in that category is just one more multiplication away. Temperature is the one category that isn’t a simple scaling, since Celsius, Fahrenheit, and Kelvin scales don’t share a zero point, so those conversions go through the correct offset formulas instead.
How accurate are the conversions?
The unit definitions use standard conversion factors, such as exactly 0.3048 meters to a foot or 1609.344 meters to a mile, matching the internationally agreed definitions rather than rounded approximations. The volume units built on US customary measures (cups, tablespoons, teaspoons, fluid ounces, gallons) use the US definitions specifically, since those measures differ from imperial ones used elsewhere.
Does the number I type get sent anywhere?
No, every conversion happens in your browser using plain arithmetic, so the value you type never gets sent anywhere. That’s useful for one-off conversions like recipe measurements or a quick unit check while building a spreadsheet, without needing to trust a third-party API with your data.
What is this useful for?
Use it to convert a recipe from cups to milliliters, check a car’s speed in mph against km/h, translate a weather forecast’s Celsius into Fahrenheit, or convert a tire’s PSI into bar. See the NIST guide to the SI for background on the base units these conversions build on.