Convert between units of length, weight, volume, temperature, speed, and area instantly. Supports both metric and imperial systems with real-time results.
| Category | Common Conversion |
|---|---|
| Length | 1 inch = 2.54 cm | 1 mile = 1.609 km |
| Weight | 1 lb = 0.454 kg | 1 oz = 28.35 g |
| Volume | 1 gallon = 3.785 L | 1 fl oz = 29.57 mL |
| Temperature | °F = (°C × 9/5) + 32 |
| Speed | 1 mph = 1.609 km/h | 1 knot = 1.852 km/h |
| Area | 1 acre = 4,047 m² | 1 sq mi = 2.59 km² |
The metric system scales by powers of ten, so conversions are decimal point moves rather than arbitrary multipliers.
| Prefix | Factor | Prefix | Factor |
|---|---|---|---|
| kilo- | 1,000 | centi- | 0.01 |
| hecto- | 100 | milli- | 0.001 |
| deca- | 10 | micro- | 0.000001 |
Several imperial-metric relationships are defined exactly rather than approximated:
Most conversions are a single multiplication, but temperature scales have different zero points, so an offset is needed:
This is why you cannot convert a temperature difference the same way as a temperature. A rise of 10 °C is a rise of 18 °F, not 50 °F — the offset applies to points on the scale, not to intervals.
A US gallon is about 3.785 litres; an imperial gallon is about 4.546. The imperial gallon is roughly 20% larger, which quietly distorts fuel economy comparisons and recipe conversions between US and UK sources. US and imperial pints, quarts and fluid ounces differ too.
When precision matters, state which system a figure came from rather than assuming.