The SI system is the world's most widely used system of measurement.

The Seven SI Base Units

The seven base units are used to form all other units.

International System of Units (SI) The Seven SI Base Units

SI Units with Special Names

Extracted from NIST.SP.330‑2019

Powers Larger Than 1

Powers Smaller Than 1

To convert from kilometres to metres, multiply by 1000.

To convert from metres to kilometres, divide by 1000.

1 metre = 100 centimetres

To convert from metres to centimetres, multiply by 100.

To convert from centimetres to metres, divide by 100.

1 centimetre = 10 millimetres

To convert from centimetres to millimetres, multiply by 10.

To convert from millimetres to centimetres, divide by 10.

1 km = 1,000 m = 100,000 cm = 1,000,000 mm

1 mm = 0.1 cm = 0.001 m = 0.000001 km

6 feet = 6 × 0.3048 m = 1.8288 m

15 m = 15 ÷ 0.3048 = 49.21 feet

1 tonne = 1000 kilogrammes

To convert from tonnes to kilogrammes, multiply by 1000.

To convert from kilogrammes to tonnes, divide by 1000.

1 kilogramme = 1000 grammes

To convert from kilogrammes to grammes, multiply by 1000.

To convert from grammes to kilogrammes, divide by 1000.

1 gramme = 1000 milligrammes

To convert from grammes to milligrammes, multiply by 1000.

To convert from milligrammes to grammes, divide by 1000.

1 ounce = 2.834952 × 10⁻² kg
1 pound = 0.45359237 kg
1 stone = 6.350293 kg

16 ounces = 1 pound
14 pounds = 1 stone
28 pounds = 1 quarter
4 quarters = 1 hundredweight
20 hundredweight = 1 ton

1 m³ = 1000 litres

To convert from cubic metres to litres, multiply by 1000.

To convert from litres to cubic metres, divide by 1000.

1 litre = 1000 cm³ = 1000 ml

To convert from litres to cubic centimetres, multiply by 1000.

To convert from cubic centimetres to litres, divide by 1000.

To convert from litres to millilitres, multiply by 1000.

To convert from millilitres to litres, divide by 1000.

1 ml = 1 cm³

1 m³ = 1000 l = 1,000,000 cm³ = 1,000,000 ml

1 litre = 100 centilitres

To convert from litres to centilitres, multiply by 100.

To convert from centilitres to litres, divide by 100.

1 cl = 10 ml

To convert from centilitres to millilitres, multiply by 10.

To convert from millilitres to centilitres, divide by 10.