Convert units
Pick the measurement, the two units and the value. The table lists every equivalent.
- foot0.08333333333 ft
- yard0.02777777778 yd
- mile0.000015782828 mi
- nautical mile0.000013714903 nmi
- millimeter25.4 mm
- centimeter2.54 cm
- meter0.0254 m
- kilometer0.0000254 km
How unit conversion works
Every unit has a factor that ties it to a base unit for its category: meter, kilogram, liter, second, bit, joule, or pascal. To convert, multiply by the factor of the starting unit and divide by the factor of the target unit.
Pick the measurement, then the two units and the value. The imperial and U.S. units are listed first, followed by the metric ones. A swap button flips the direction.
Everyday conversions
| Unit | Equals | Used for |
|---|---|---|
| 1 inch | 25.4 mm | Screens, hardware, pipe sizes |
| 1 foot | 0.3048 m | Height, room dimensions |
| 1 mile | 1.609344 km | Driving distance, running |
| 1 ounce (weight) | 28.3495 g | Food, mail, jewelry |
| 1 pound | 0.45359237 kg | Body weight, groceries |
| 1 U.S. gallon | 3.785411784 L | Gas, paint, milk |
| 1 U.S. cup | 236.588 mL | Recipes |
| 1 U.S. fluid ounce | 29.5735 mL | Drinks, medicine doses |
The inch, foot, yard, mile, ounce, and pound are defined exactly in metric terms, so these factors are exact, not rounded.
Temperature and special cases
| Fahrenheit | Celsius | What it means |
|---|---|---|
| −40 °F | −40 °C | The two scales meet |
| 32 °F | 0 °C | Water freezes |
| 68 °F | 20 °C | Room temperature |
| 98.6 °F | 37 °C | Typical body temperature |
| 212 °F | 100 °C | Water boils at sea level |
- U.S. and imperial gallons are different sizes: 3.785 L versus 4.546 L. The tool lists both, labeled.
- Storage has two systems: a gigabyte is 1,000³ bytes, and a gibibyte is 1,024³ bytes.
- The food Calorie (Cal) is 1 kilocalorie. The tool uses the thermochemical calorie: 1 cal = 4.184 J.
- The tool rejects temperatures below absolute zero (−459.67 °F).
Planning a room or a yard? The square footage calculator works in square feet. Working with digital sizes in other number systems? See the number base converter.
Frequently asked questions
How many kilometers are in a mile?
One mile is exactly 1.609344 kilometers. So 5 miles is 8.04672 km, and a 26.2-mile marathon is about 42.16 km.
How do I convert pounds to kilograms?
Multiply pounds by 0.45359237. For example, 150 lb × 0.45359237 = 68.04 kg.
How do I convert Fahrenheit to Celsius?
Subtract 32, then multiply by 5 and divide by 9. So 68 °F gives (68 − 32) × 5 ÷ 9 = 20 °C.
How many cups are in a gallon?
A U.S. gallon holds 16 cups. That also equals 4 quarts, 8 pints, or 128 fluid ounces.
How many ounces are in a pound?
A pound has 16 ounces by weight. Fluid ounces measure volume instead, so 16 fluid ounces make a U.S. pint.
How many inches are in a foot?
A foot has 12 inches, and an inch is exactly 25.4 millimeters, so a foot is 304.8 mm.
Sources and method
- NIST, Guide for the Use of the International System of Units (SP 811)
- International Yard and Pound Agreement of 1959 (exact inch and pound definitions)