Unit Converter
Convert length, mass, temperature, time, speed, area, volume and computer data in one place — and see the formula and working behind every answer, plus the value in every other unit at once.
To convert units, multiply by the conversion factor: a bigger unit to a smaller one multiplies, a smaller to a bigger divides. So 3 km = 3 × 1000 = 3000 m, and 250 cm = 250 ÷ 100 = 2.5 m. Temperature is the exception: °F = °C × 9/5 + 32, so 37 °C = 98.6 °F.
Length
Type a value — the answer updates as you type.
Formula used
All units
Tap a row to convert to that unit.
| Unit | Value |
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Common school conversions
One tap fills the converter with a textbook-style question.
SI prefixes
The same prefixes work for metres, grams, litres, seconds and bytes.
Mnemonic: King Henry Died By Drinking Chocolate Milk. Each step down the ladder multiplies by 10; each step up divides by 10.
| Prefix | Symbol | Power of 10 | Multiplier | Example |
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Every conversion is a multiplication
Except temperature, converting units means multiplying or dividing by a fixed conversion factor — the converter shows you which one.
Pick a category
Length, mass, temperature, time, speed, area, volume or data.
Choose the units
Select the unit you have and the one you want. Use the swap button to reverse.
Type the value
The answer, formula and working update instantly as you type.
Compare all units
The table shows your value in every unit of that category.
Big unit → small unit
Going from a bigger unit to a smaller one gives a bigger number, so multiply: 3 km = 3 × 1000 = 3000 m. Going from small to big, divide: 250 cm = 250 ÷ 100 = 2.5 m.
Temperature is different
°F = °C × 9/5 + 32
K = °C + 273.15
Water freezes at 0 °C = 32 °F = 273.15 K and boils at 100 °C = 212 °F. Normal body temperature is about 37 °C = 98.6 °F.
Area and volume units
Square the length factor for area and cube it for volume: 1 m = 100 cm, so 1 m² = 100² = 10,000 cm² and 1 m³ = 100³ = 10,00,000 cm³ = 1000 L.
Speed trick: km/h × 5/18 = m/s, and m/s × 18/5 = km/h.
Unit Converter — your questions
How do I convert cm to m and m to km?
Going from a smaller unit to a bigger one, divide: 250 cm ÷ 100 = 2.5 m, and 4500 m ÷ 1000 = 4.5 km. Going the other way, multiply: 3 km × 1000 = 3000 m. The metric system always uses powers of ten, which is why only the decimal point moves.
How do you convert Celsius to Fahrenheit?
Use °F = °C × 9/5 + 32. So 37 °C becomes 37 × 1.8 + 32 = 98.6 °F, which is normal body temperature. To reverse it, use °C = (°F − 32) × 5/9. Water freezes at 0 °C = 32 °F and boils at 100 °C = 212 °F.
How do I convert km/h to m/s?
Multiply by 5/18, because 1 km = 1000 m and 1 hour = 3600 seconds, and 1000 ÷ 3600 simplifies to 5/18. So 72 km/h = 72 × 5/18 = 20 m/s. To go back from m/s to km/h, multiply by 18/5 instead, so 15 m/s = 54 km/h. Physics numericals almost always need the speed in m/s before you substitute.
Why is 1 m² equal to 10,000 cm² and not 100 cm²?
Area has two dimensions, so the length factor is squared: 1 m = 100 cm means 1 m² = 100² = 10,000 cm². Volume has three dimensions, so the factor is cubed: 1 m³ = 100³ = 10,00,000 cm³. Forgetting to square or cube the factor is the commonest conversion mistake.
How many cubic centimetres are there in a litre?
One litre is exactly 1000 cm³, and one millilitre is the same as 1 cm³. One cubic metre holds 1000 litres. So a water tank measuring 2 m by 1.5 m by 1 m has a volume of 3 m³ and holds 3000 litres. Convert every side to the same unit before multiplying, or the answer will be out by a factor of a thousand.
Does temperature conversion work like the other units?
No. Every other category converts by multiplying or dividing by a fixed factor, because zero means the same thing in both units. Temperature scales have different zero points, so you must add or subtract as well as multiply. Kelvin is the exception that only shifts: K = °C + 273.15.