Unit Converters

Convert any everyday unit as you type. Length, weight, volume, speed, time, temperature, area, data storage, pressure, fuel economy and energy are covered, plus a height converter and a weight-to-volume tool for questions like how many liters are in a kilogram. Every page shows the exact factor, the formula and a conversion table you can use offline.

All unit converters calculators

How these converters work

Each unit is stored as an exact factor to a base unit (the meter, the kilogram, the liter, the second), and a conversion is a multiply and a divide, so results are as precise as the definitions themselves. The inch, foot, yard, mile, pound and gallon all have exact metric definitions, so 1 mile is exactly 1.609344 km and 1 pound is exactly 0.45359237 kg. Temperature is the exception because its scales have different zero points, so the converter applies the offset as well as the ratio.

Some popular searches mix two different kinds of unit. Kilograms to liters depends on the density of the substance, so that page lets you pick water, milk, oil, petrol and others. Feet to square feet needs a width as well as a length, which the area converter handles.

Frequently asked questions

Which spelling do you use, meter or metre?

The pages use meter and liter (the US spelling) in headings, and the converters accept either. Metre, litre, kilometre and centimetre are the same units with the British spelling, and the factors are identical.

Are the conversion factors exact?

Yes for units with a formal definition: the international inch (25.4 mm), foot (0.3048 m), pound (0.45359237 kg), US gallon (3.785411784 L) and imperial gallon (4.54609 L). Results are rounded to eight significant digits for display, which is more than enough for any everyday use.

Why does kg to liters need a substance?

Kilograms measure mass and liters measure volume, so the answer depends on how dense the material is. One kilogram of water is exactly one liter, but a kilogram of cooking oil is about 1.09 liters and a kilogram of honey is only about 0.7 liters. The kg to liter converter includes a density list for common liquids and dry goods.

Last updated . Formulas are shown on the page and checked against the worked example.