Common conversions
- 1 inch = 2.54 centimeters (exact) · 1 mile = 1.609344 kilometers
- 1 pound = 0.45359237 kilograms (exact) · 1 kilogram ≈ 2.2046 pounds
- °F = °C × 9/5 + 32 · °C = (°F − 32) × 5/9 · K = °C + 273.15
- 1 US gallon = 3.785 liters · 1 imperial gallon = 4.546 liters
- 1 acre = 43,560 square feet ≈ 4,047 square meters
KB vs. KiB
Storage makers use decimal units (1 KB = 1,000 bytes), while operating systems often use binary units (1 KiB = 1,024 bytes). That's why a "1 TB" drive shows up as about 931 GiB.
Quick conversion tables
Length
| From | To | Multiply by |
|---|---|---|
| Inches | Centimeters | 2.54 |
| Feet | Meters | 0.3048 |
| Yards | Meters | 0.9144 |
| Miles | Kilometers | 1.609 |
| Kilometers | Miles | 0.6214 |
| Meters | Feet | 3.281 |
Weight
| From | To | Multiply by |
|---|---|---|
| Ounces | Grams | 28.35 |
| Pounds | Kilograms | 0.4536 |
| Kilograms | Pounds | 2.205 |
| Stone | Pounds | 14 |
Cooking volumes (U.S.)
| Measure | Equals | Milliliters |
|---|---|---|
| 1 teaspoon | 1/3 tablespoon | 4.93 mL |
| 1 tablespoon | 3 teaspoons | 14.8 mL |
| 1 fluid ounce | 2 tablespoons | 29.6 mL |
| 1 cup | 8 fluid ounces | 237 mL |
| 1 pint | 2 cups | 473 mL |
| 1 quart | 2 pints | 946 mL |
| 1 gallon | 4 quarts | 3.785 L |
Temperature
| Description | Celsius | Fahrenheit |
|---|---|---|
| Water freezes | 0 °C | 32 °F |
| Room temperature | 20 °C | 68 °F |
| Normal body temperature | 37 °C | 98.6 °F |
| Water boils (at sea level) | 100 °C | 212 °F |
| Moderate oven | 180 °C | 356 °F |
| The two scales meet | −40 °C | −40 °F |
Frequently asked questions
Why are U.S. and imperial gallons different?
They come from different historical definitions. A U.S. gallon is 3.785 liters and an imperial (UK) gallon is 4.546 liters — about 20% larger. Pints and fluid ounces differ too, so check which system a recipe or fuel-economy figure uses.
What's a quick way to convert Celsius to Fahrenheit in my head?
Double it and add 30. It's an approximation — 20 °C gives 70 °F instead of the exact 68 °F — but it's close enough for the weather. For Fahrenheit to Celsius, subtract 30 and halve.
Is a metric ton the same as a U.S. ton?
No. A metric ton (tonne) is 1,000 kg, about 2,205 lb. A U.S. "short" ton is 2,000 lb, and the British "long" ton is 2,240 lb.
What's the difference between mass and weight?
Mass is the amount of matter in an object and is the same everywhere; weight is the force of gravity on it. In everyday use on Earth the two are treated as the same thing, which is why kilograms and pounds are used interchangeably for "weight".
How precise are these conversions?
Conversions between metric and U.S. customary units are based on exact legal definitions (for example, 1 inch = 2.54 cm exactly), so results are limited only by rounding. Results are shown to up to 10 significant digits.