SI units

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

The 7 base units are used to make other units.

International System of Units (SI)

The seven SI base units

 

The 22 SI units with special names and symbols

Extracted from NIST.SP.330-2019.pdf

 

SI Prefixes

Powers larger than 1

Powers less than 1

 

Lengths

 1 kilometre = 1000 metres

 

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

 

Imperial to Metric

Examples

6 feet = 6 x 0.3048m = 1.8288 m

15m = 15 ÷0.3048 = 49.21 feet

Imperial units

Unitary method for converting units

Mass

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

 

Imperial to Metric

1 ounce = 2.834952 x 10^-2 kg
1 pound = 0.45359237 kg
1 stone = 6.350293 kg

Imperial units

6 ounces (oz) = 1 pound 
14 pounds (lb) =  1 stone
28 pounds = 1 quarter
4 quarters = 1 hundredweight
20 hundredweight (cwt) = 1 ton

VOLUME

To convert from cubic metres to litres, multiply by 1000

To convert from litres to cubic metres, divide by 1000

 

1 Litre  = 1000 cubic centimetres ( cm³ )
= 1000 millilitres ( 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 cubic centimetres to litres, divide by 1000

1 millilitre  ( ml ) = 1 cubic centimetre (cm³ )

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

1 Litre = 100 Centilitres ( cl )

To convert from litres to centilitres, multiply by 100

To convert from to centilitres to litres , divide by 100

 

 

1 centilitre  ( cl ) = 10 mililitres

 

To convert from centilitres to millilitres, multiply by 10.

To convert from millilitres to centilitres, divide by 10.

 

 

Imperial to Metric

   1 fluid ounce = 2.841306 x 10^-5 m³
    1 gallon = 4.54609 x 10^-3 m³
   1 gallon USA = 3.785412 x 10^-3 m³

20 fluid ounces  (fl. oz) = 1 pint
2 pints (pt) = 1 quart
4 quarts = 1 gallon

One gallon is the volume occupied by exactly 10 pounds of water of density 0.988859 gram per millilitre , weighed in air of density 0.001217 gram per millilitre against weights of density 8.136 grams per millilitre.

Unitary method for converting units