Convert length, weight, and temperature between metric and imperial units instantly.
One mile is 1.609344 kilometres exactly (by international definition since 1959). One inch is 2.54 centimetres exactly. When converting between metric and imperial, always check whether you need to be exact or rounded.
One kilogram equals 2.20462 pounds. One pound equals 16 ounces. For everyday cooking, 100g is roughly 3.5oz and 500g is about 1lb 2oz. The metric tonne (1,000 kg) is different from the US ton (2,000 lb) and the British long ton (2,240 lb).
To convert Celsius to Fahrenheit: multiply by 9/5, then add 32. To go the other way: subtract 32, then multiply by 5/9. Key reference points: water freezes at 0°C (32°F) and boils at 100°C (212°F). Normal body temperature is 37°C (98.6°F).
Kelvin is the SI base unit of temperature used in science. Zero Kelvin (absolute zero, −273.15°C) is the lowest possible temperature — the point at which all molecular motion stops. There are no negative Kelvin values.
Convert length, weight, and temperature between metric and imperial units. Select a category, enter a value, choose your units, and click Convert.
5 miles to kilometres
8.0467 km
100°F to Celsius
37.78°C
70 kg to pounds
154.32 lbs
12 inches to centimetres
30.48 cm
Celsius to Fahrenheit
25°C = 77°F
Miles to kilometres
10 miles = 16.09 km
Pounds to kilograms
150 lbs = 68.04 kg
The metric system was first introduced in France in 1799 during the French Revolution, replacing a chaotic variety of local measurement systems. Britain officially adopted the metric system for trade in 1965, though imperial units (miles, pints, pounds) are still widely used in everyday life. The US is one of only three countries in the world that has not officially adopted the metric system, alongside Liberia and Myanmar.
Multiply the number of miles by 1.60934. For example, 10 miles × 1.60934 = 16.09 km. The relationship is exact by international definition: one international mile equals 1.609344 kilometres.
Use the formula: °F = (°C × 9/5) + 32. So 20°C = (20 × 1.8) + 32 = 68°F. Key reference points: 0°C = 32°F (freezing), 100°C = 212°F (boiling), 37°C = 98.6°F (body temperature).
Multiply kilograms by 2.20462. For example, 70 kg × 2.20462 = 154.32 lbs. To go from pounds to kilograms, divide by 2.20462 (or multiply by 0.453592).
A metric tonne is exactly 1,000 kilograms (about 2,204.6 lbs). A US short ton is 2,000 pounds (about 907 kg). A British long ton is 2,240 pounds (about 1,016 kg). Always clarify which 'ton' is meant in international contexts.
Absolute zero is 0 K, equivalent to −273.15°C or −459.67°F. It is the lowest temperature theoretically possible — the point at which all thermal motion of particles stops. Kelvin is the SI unit of temperature used in science and engineering.