Convert length, area, mass, volume and temperature

How to convert units

Choose the quantity — length, area, mass, volume or temperature. Then specify which unit you are converting from and to, and enter the value. The “Swap” button reverses the direction: handy when you need to check the reverse conversion and make sure the numbers agree.

For example, to find out how many sotkas there are in a plot of 12 acres, choose “Area”, set “From: Acre” and “To: Sotka”, and enter 12. The result is 485.6 sotkas: an acre is defined as 4046.86 m², and a sotka is exactly 100 m².

Where the coefficients come from

All imperial units are now defined through metric ones: an inch is exactly 25.4 mm, a pound is 0.45359237 kg, a US gallon is 3.785411784 litres. That is why conversions within the metric system are exact, while imperial ones give an exact result by definition, just with a long decimal fraction. The calculator rounds to six significant digits — more is not needed for everyday tasks.

Why temperature is separate

Metres and feet share the same zero, so converting is multiplying by a coefficient. Temperature scales have different zeros: 0 °C is 32 °F and 273.15 K. A linear factor is not enough, a formula with an offset is needed, so the calculator converts temperature through intermediate degrees Celsius. Kelvin cannot be negative — such values are rejected.

For cooking recipes, remember that a “cup” in the US and in the metric system are different volumes. The converter uses US liquid units unless stated otherwise.