Unit converter
Convert between the most common units of length, weight, temperature, volume and speed. The result updates instantly as you type.
Metric versus imperial
A good share of everyday conversions come down to switching between the metric system (metres, kilos, litres, Celsius), used across most of the world, and the imperial system (miles, pounds, gallons, Fahrenheit), still common in the United States and, in parts, the United Kingdom. We bump into it reading a foreign recipe, shopping online, travelling or following a product's specifications.
The conversions people search for most
- Temperature: Celsius to Fahrenheit, multiply by 9, divide by 5 and add 32. 20 °C is 68 °F.
- Distance: a mile is about 1.61 km; a foot, about 30.48 cm; an inch, 2.54 cm.
- Weight: a pound is about 0.454 kg; an ounce, about 28.35 g.
- Volume: here's the trap, because the US gallon (3.785 l) isn't the same as the imperial gallon (4.546 l).
Don't assume a unit is unique
The gallon is the best-known example, but not the only one: an American recipe "cup" isn't the same as a British one, and an ounce of weight isn't a fluid ounce. So, when converting, it pays to note the system you're starting from. The tool keeps these cases apart so you don't get a surprise halfway through a recipe or an order.
Exact and approximate conversions
Some equivalences are exact by definition (an inch is precisely 2.54 cm), while others are rounded. For most everyday uses, two decimals are plenty; only technical or scientific work needs more precision. Everything is worked out in your browser, instantly.