Unit Converter
Convert length, weight, volume, area, speed, pressure, energy, and data storage in one tool.
How to use the unit converter
Pick a category first, like length or weight. Type the number you want to convert, choose the unit you are starting from, and pick the unit you want. The result shows as you type, and the swap button flips the two units when you need to go the other way.
Changing the category resets the fields, so you start each conversion clean. A blank or non-numeric entry stays in the empty state instead of showing an error, and negative values are turned away because none of these quantities can be below zero.
What this converter covers
One tool handles eight kinds of unit, each with its own list:
- Length, from millimeters to nautical miles, and area, from square meters to acres.
- Weight, from milligrams to US tons, and volume, from milliliters to gallons.
- Speed in m/s, km/h, mph, and knots.
- Pressure in bar, psi, atm, and more, plus energy in joules, calories, and kilowatt-hours.
- Data storage, with both decimal (KB, MB, GB) and binary (KiB, MiB, GiB) units side by side.
Need just one type? The length converter and weight converter are focused single-purpose versions of the same engine.
How the conversion works
Every unit in a category is stored as a factor against one base unit. Meters are the base for length, grams for weight, liters for volume. To convert, the tool multiplies your value by the starting unit's factor to reach the base, then divides by the target unit's factor.
So 10 kilometers becomes 10,000 meters, then divides by 1609.344 to give 6.21 miles. The same two-step method works for every category, which is why one engine can serve them all. Results show up to six significant figures, with very large or small numbers in compact scientific notation.
Why temperature is separate
Temperature does not fit the factor method. Converting Celsius to Fahrenheit needs an add-and-multiply step, not a single multiplier, because the two scales start from different zero points. A factor alone would give the wrong answer.
For that reason temperature has its own tool. Use the temperature converter for Celsius, Fahrenheit, and Kelvin. For motion units you can also use the dedicated speed converter.
Frequently asked questions
- What units can I convert here?
- Length, weight, volume, area, speed, pressure, energy, and data storage. Pick a category at the top, and the from and to lists update to that quantity. Temperature has its own dedicated tool.
- How accurate are the conversions?
- Each unit uses a precise factor against a base unit, so results are accurate to six significant figures. Common pairs like kilometers to miles or kilograms to pounds match standard reference values.
- Why is temperature not included?
- Temperature scales need an offset, not just a multiplier, since Celsius and Fahrenheit start from different zero points. A factor-only tool would be wrong, so temperature uses its own converter.
- What is the difference between KB and KiB?
- A kilobyte (KB) is 1,000 bytes, the decimal unit drive makers use. A kibibyte (KiB) is 1,024 bytes, the binary unit operating systems use. Both appear in the data storage list so you can pick the right one.
- Why does it not accept negative numbers?
- Length, weight, volume, and the other quantities here cannot be below zero. The tool shows a short prompt instead of a result, rather than returning a value that has no physical meaning.