Unit Converter - 120+ Units

Each unit is stored with a conversion factor relative to a base unit in its category (e.g., meters for length). Converting between units multiplies the input by the source factor, then divides by the target factor. Temperature uses dedicated formulas since Celsius, Fahrenheit, and Kelvin are offset-based rather than ratio-based. All math runs in JavaScript with no server calls.

There are 14 categories: Length, Weight/Mass, Temperature, Volume, Speed, Area, Data Storage, Time, Energy, Pressure, Frequency, Angle, Fuel Economy, and Force. Each category includes common everyday units plus advanced units for scientific and engineering work.

Yes. All conversions use exact mathematical constants and formulas with full floating-point precision. You can enable Decimal mode to see values with 10 significant digits and trailing zeros for maximum precision.

Yes. Every applicable category supports both metric and imperial units. For example, you can convert between kilometers and miles, kilograms and pounds, Celsius and Fahrenheit, liters and gallons, or PSI and atmospheres.

When Lock Value is on, switching the source unit recalculates the input so the converted values stay the same. For example, if you enter 1 kilometer and switch to miles, the input changes to 0.621371 miles. Turn it off to keep the same number and just change the unit.

Toggle Advanced mode to reveal less common units like femtometers, angstroms, light-years, Rankine, Mach, nautical miles, and more. The setting is saved in your browser so it stays on across visits.

For certain units, the converter shows a secondary notation breaking the value into larger mixed units. For example, a time conversion might show "2 yr, 3 mo, 15 d" alongside the raw number of days, or a weight might show tons and remaining pounds.

Each category includes a collapsible reference panel with real-world benchmarks to give context to your conversions. For example, the length category shows the Earth-to-Moon distance, and the speed category lists the speed of sound and light.

Yes. All conversion formulas are built into the page with pure JavaScript. Once loaded, no internet connection is needed.