About the Unit Converter
The Unit Converter handles thirteen kinds of measurement on one page: length, weight and mass, temperature, volume, area, speed, time, data size, energy, power, pressure, angle and frequency. Pick a category, type a number, choose the two units, and the answer appears as you type, together with the value in every other unit of that category.
It covers the everyday conversions between US customary and metric units, like feet to meters, pounds to kilograms, gallons to liters and miles per hour to kilometers per hour. It also handles the ones that trip people up, such as gigabytes versus gibibytes, US versus imperial gallons, kilowatt-hours to BTU, and psi to bar.
Conversion factors use the exact legal definitions wherever they exist: an inch is exactly 2.54 centimeters, a pound exactly 0.45359237 kilograms. You choose the precision, and every result can be copied with one click. Everything runs in your browser.
How to use it
- Pick a categoryClick Length, Weight and mass, Temperature, Volume, Area, Speed, Time, Data size, Energy, Power, Pressure, Angle or Frequency.
- Enter a valueType the number to convert in the From box. Decimals, negative numbers and values like 1e6 all work.
- Choose the unitsSelect the From and To units, click the swap button to reverse them, or use one of the Common buttons for a popular pair.
- Read the result and the factorThe result appears in the To box. The line underneath shows the factor, such as "multiply by 0.3048", so you can reuse it.
- See every unit and copyThe "In every unit" list shows the value in all units of the category. Pick a precision and copy any result.
Key features
13 categories, 147 units
From millimeters to light years, grains to metric tons, teaspoons to oil barrels, bits to tebibytes, and more.
Exact factors
Uses the exact definitions of the inch, foot, mile, pound, ounce, US gallon, imperial gallon and nautical mile, among others.
Every unit at once
One input fills a whole list, so you can compare units side by side without converting again.
Adjustable precision
Show 4, 6, 10 or 15 significant digits. Very large and very small numbers switch to scientific notation.
Copy-ready numbers
Copy buttons give plain numbers without thousands separators, ready for a spreadsheet or code.
Private by design
No account, no upload, and it keeps working once the page has loaded.
Examples
Everyday conversions
| From | To | Factor |
|---|---|---|
| 1 meter | 3.280839895 feet | × 3.280839895 |
| 5 kilometers | 3.106855961 miles | × 0.6213711922 |
| 1 US gallon | 3.785411784 liters | × 3.785411784 |
| 1 US cup | 236.5882365 milliliters | × 236.5882365 |
| 1,000 square feet | 92.90304 square meters | × 0.09290304 |
| 60 mph | 96.56064 km/h | × 1.609344 |
| 1 kWh | 3,412.141633 BTU | × 3,412.141633 |
| 32 psi | 2.206322334 bar | × 0.06894757293 |
Results use 10 significant digits by default. Switch to 4 digits for everyday use (3.281 feet), or 15 digits when you need every decimal: 1 kilogram is 2.20462262184878 pounds.
Gigabytes or gibibytes?
| Size | In binary units |
|---|---|
| 1 GB | 0.9313225746 GiB |
| 500 GB | 465.6612873 GiB |
| 1 TB | 0.9094947018 TiB |
Drive makers use decimal units, where 1 GB is 1,000,000,000 bytes. Many operating systems count in binary units of 1,024, and Windows still labels them "GB". That is why a new 500 GB drive shows up as about 465 "GB". Internet speeds use bits: 100 megabits per second moves 12.5 megabytes per second.
Same name, different size
| Unit | Value |
|---|---|
| 1 US gallon | 3.785411784 liters |
| 1 imperial gallon | 4.54609 liters |
| 1 short ton (US) | 907.18474 kilograms |
| 1 metric ton | 1.102311311 short tons |
| 1 troy ounce | 1.097142857 ounces |
Recipes, fuel economy figures and shipping weights from other countries often use the other version, so check which one is meant.
Time and averages
One week is exactly 168 hours. Months and years have no fixed length, so the converter uses the average of the Gregorian calendar: 1 year is 365.2425 days and 1 month is 30.436875 days. For the number of days between two real dates, use the Date Difference Calculator.
In the Temperature category, a value below absolute zero, such as -300 °C, shows a warning, because nothing can be colder than 0 K.
Tips
- Use the Common buttons for popular pairs like meters to feet or liters to gallons, then click the swap button to convert the other way.
- Copy the factor from the formula line into a spreadsheet. Multiply a whole column by it to convert a list of values at once.
- Lower the precision to 4 or 6 digits for recipes and travel. Keep 10 or more for engineering, science and money calculations.
- When a value looks off by about 7% in data sizes, check whether one side uses GB and the other GiB.
- For a single unit family with more detail, the Length, Weight and Temperature converters have the same engine on their own pages.
Common mistakes and limits
- Mixing US and imperial unitsA US gallon is about 17% smaller than an imperial gallon, and a US fluid ounce differs from an imperial one. Pick the version that matches your source.
- Confusing weight and troy weightGold and silver are priced in troy ounces, which are about 10% heavier than the ounces on a kitchen scale.
- Treating months and years as exactThe converter uses calendar averages. A real month has 28 to 31 days, and a real year 365 or 366.
- Mixing bits and bytesA lowercase b usually means bits, an uppercase B bytes. 100 Mbit/s is 12.5 MB/s, not 100.
- Copying numbers with commas into codeThe results on screen use thousands separators for readability. Use the Copy buttons, which give plain numbers such as 3412.141633.