Converting units without mistakes
Most of the world measures in metric units, while the United States uses miles, pounds, gallons and degrees Fahrenheit in everyday life. Recipes, travel plans, workout logs, shipping weights and technical specifications all cross that border regularly, and a wrong conversion factor can be expensive.
This converter covers length, mass, temperature, area, volume, time and digital data. Pick a category, a from-unit and a to-unit, and the result appears as you type, ready to copy.
How to use it
- Choose a category: Length, Mass, Temperature, Area, Volume, Time or Data.
- Type the value you want to convert.
- Pick the unit you are converting from and the unit you want.
- Read the result and copy it with the button. Round it to the precision your task needs.
Example: three everyday conversions
5 Kilometer to Mile 100 Fahrenheit to Celsius 1 Gigabyte to Megabyte
3.1068559611866697 Mile 37.77777777777777 Celsius 1024 Megabyte
The result is shown at full precision, so round it yourself: a 5 km run is 3.11 miles, and 100 °F is about 37.8 °C.
Exact definitions behind the numbers
Since the international yard and pound agreement of 1959, the imperial units used in the US are defined from metric ones: one inch is exactly 2.54 cm, one foot exactly 0.3048 m, one mile exactly 1,609.344 m, and one pound exactly 0.45359237 kg. The factors on this page use those exact definitions, so conversions are as precise as the floating-point numbers that carry them.
Volume is the classic trap. A US gallon is 3.785 litres, but the imperial gallon used in the UK is 4.546 litres. This converter uses US units throughout, as labelled.
Temperature is different
Temperature scales do not share a zero point, so they cannot be converted by multiplying alone. Celsius to Fahrenheit is °F = °C × 9/5 + 32, and Kelvin is Celsius plus 273.15. A temperature difference is converted without the offset: a rise of 10 °C is a rise of 18 °F, not 50 °F.
Data units: 1000 or 1024?
This converter uses binary multiples: one kilobyte is 1,024 bytes and one gigabyte is 1,024 megabytes, the way most operating systems report memory and file sizes. Storage makers and the SI standard use decimal multiples instead, 1 GB = 1,000,000,000 bytes, which is why a new 1 TB drive appears as about 931 GB on a computer. The strict names for the binary units are KiB, MiB and GiB. Bits are an eighth of a byte, and network speeds are quoted in bits per second.
Questions
How long is a month or a year here?
For time conversions, a month is 30 days and a year is 365 days, as the labels say. Calendar months and leap years vary, so use a date tool for exact calendar spans.
Can I convert cooking measures?
Yes, under Volume: US cups, pints, quarts, gallons and fluid ounces. For flour or sugar by weight you need the ingredient's density, which differs per ingredient.
Is there a stone unit for body weight?
Yes. One stone is 14 pounds, about 6.35 kg, and is listed under Mass.