To convert units, pick a category such as Length or Weight, type the number in the From Unit box, and choose the source and target units from the two lists. The result appears instantly in the To Unit box and in words below it. Select Swap & Convert to reverse the direction, or Copy Result to copy it.
How to use the unit converter
- Choose a category. Select one of the 12 category buttons. Each one loads sensible defaults, such as kilograms to pounds for Weight.
- Enter a value. Type the number in the From Unit box. Decimals and negative numbers are fine.
- Pick the units. Choose them from the source and target lists, or type part of a name such as "inch" or "kg" in the search box above each list to filter it.
- Use the result. Read it in the To Unit box, with a rounded and a scientific version below. Select Copy Result or tap a Common Conversions preset to try another.
What the unit converter covers
The measurement converter has 12 categories and the units listed below. Volume units are US measures, so a gallon is the US gallon of 3.785 liters. Currencies aren't included because rates change every day; use the currency converter for money.
| Category | Units |
|---|---|
| Length | m, km, cm, mm, µm, nm, mile, yard, foot, inch, nautical mile |
| Weight | kg, g, mg, µg, metric ton, pound, ounce, stone |
| Area | m², km², cm², mm², hectare, acre, ft², yd² |
| Volume | liter, mL, cL, m³, cm³, US gallon, quart, pint, cup, fluid ounce |
| Temperature | Celsius, Fahrenheit, Kelvin, Rankine |
| Speed | m/s, km/h, mph, ft/s, knot |
| Time | ms, second, minute, hour, day, week, month (average), year (365 days) |
| Data | bit, kbit, Mbit, Gbit, byte, kB, MB, GB, TB (1,000-based), KiB, MiB, GiB, TiB (1,024-based) |
| Pressure | Pa, kPa, bar, psi, atm, Torr |
| Energy | J, kJ, cal, kcal, Wh, kWh, eV |
| Power | W, kW, MW, horsepower, BTU per hour |
| Angle | degree, radian, gradian, turn |
Metric converter formulas: cm to inches, kg to lbs, Celsius to Fahrenheit
Most conversions multiply by a fixed factor. The converter changes your value into the category's base unit (meters, kilograms, liters and so on) and then into the target unit, using exact definitions where they exist.
- cm to inches: divide by 2.54, because an inch is defined as exactly 2.54 cm. 170 cm ÷ 2.54 = 66.93 inches, which is 5 feet 6.93 inches.
- kg to lbs: a pound is exactly 0.45359237 kg, so divide by that, or multiply by about 2.2046. 70 kg = 154.32 lb.
- km to miles: a mile is 1.609344 km. 5 km ÷ 1.609344 = 3.11 miles.
- Celsius to Fahrenheit: °F = °C × 9/5 + 32. 25 °C × 9/5 = 45, plus 32 = 77 °F.
- Fahrenheit to Celsius: °C = (°F - 32) × 5/9. 98.6 °F - 32 = 66.6, × 5/9 = 37 °C.
Temperature is the one category that doesn't scale by a single factor, because 0 °C and 0 °F are different points. The converter uses direct formulas for it, and Kelvin is Celsius plus 273.15.
Weight unit converter for kitchen, gym and shipping
The Weight category covers both systems. A few conversions people look up most:
| From | To |
|---|---|
| 1 kg | 2.2046 lb |
| 1 lb | 16 oz, or 453.59 g |
| 1 oz | 28.35 g |
| 1 stone | 14 lb, or 6.35 kg |
| 1 metric ton | 1,000 kg |
For cooking, weight is more accurate than cups, but recipes often use volume. The Volume category converts US cups, pints and fluid ounces to milliliters: 1 US cup is about 236.6 mL.
Data units: why KB can mean 1,000 or 1,024 bytes
Storage makers use decimal units, where 1 KB is 1,000 bytes and 1 TB is a trillion bytes. Windows and many programs count in powers of 2, where 1 KiB is 1,024 bytes. That's why a 1 TB drive shows as about 931 GiB on a computer.
This converter keeps the two apart. kB, MB, GB and TB are decimal (1,000-based), and KiB, MiB, GiB and TiB are binary (1,024-based); each unit's label says which. To check a drive, convert 1 TB to GiB: the answer is 931.32. Megabits (Mbit) are there too, so 100 Mbit is 12.5 MB. For counting what a number is in binary or hex, try the binary to decimal converter.
Frequently asked questions
How do I convert cm to inches?
Divide centimeters by 2.54. For example, 30 cm ÷ 2.54 = 11.81 inches. In the converter, choose Length, then Centimeter as the source and Inch as the target.
How many pounds are in a kilogram?
One kilogram is about 2.2046 pounds. To convert kg to lbs, multiply by 2.2046; to go back, multiply pounds by 0.4536.
What is the formula for Celsius to Fahrenheit?
Multiply by 9/5 (or 1.8) and add 32. 20 °C is 20 × 1.8 + 32 = 68 °F.
Does the converter use US or UK gallons?
US gallons, quarts, pints, cups and fluid ounces. A US gallon is 3.785 liters. UK imperial gallons aren't included.
How long is a month in the time category?
An average month of 30.4375 days, which is 365.25 days divided by 12. A year in the converter is 365 days.
Is this a metric converter only?
No. It converts within and between metric and US customary units, and also covers units such as knots, nautical miles, Rankine and electronvolts.