Unit converter
Length, weight, area, volume and temperature
Worked out in your browser. No sign-up.
Pick what you are measuring, choose the unit you have and the unit you want, then type a number. The converter covers length (millimetres to miles, inches and feet), weight (milligrams to tonnes, and pounds), area (cm² to km², ares and hectares), volume and temperature in Celsius, Fahrenheit and kelvin. Results change as you type.
How it works
Length, weight, area and volume are converted with a fixed ratio between the two units. Area and volume need that ratio squared or cubed, which is where most mental-arithmetic slips happen: 1 m² is 10,000 cm², and 1 m³ is a full 1,000,000 cm³.
Temperature is different because the scales start at different points. °F = °C × 9/5 + 32, and K = °C + 273.15.
Worked example
A plot of 0.35 ha near a Vojvodina village is 3,500 m², or 35 ares, which is how Serbian estate agents often list land. A 0.8 m³ water tank holds 800 litres. A 27-inch monitor has a 68.58 cm diagonal, and a 20 °C day is 68 °F.
Questions people ask
How many square metres are in a hectare?
10,000. A hectare is a square 100 m on each side, and it is also 100 ares, the unit you'll see on land adverts in Serbia and much of Europe.
Is a millilitre the same as a cubic centimetre?
Yes, 1 ml = 1 cm³ exactly, so a 250 ml glass holds 250 cm³.
How many pounds is a kilogram?
About 2.2046. One pound is defined as exactly 0.45359237 kg, so 70 kg comes to roughly 154.3 lb.
Why can't temperature be converted by multiplying?
Because 0 °C isn't 0 °F. Water freezes at 32 °F, so you have to shift the scale as well as stretch it.
Sources
- BIPM: The International System of Units (SI brochure) — checked 13.11.2026
- NIST: SI conversion factors — checked 13.11.2026
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Updated: 13 November 2026