Units of Measurement in Science - Secondary 3

Concept sheet | Science and Technology

Quantities and Their Symbols

The International System of Units (SI) is an internationally recognized system. It brings together the most commonly used units of measurement in order to facilitate exchanges in the scientific, technological, and educational fields. The table below shows the most commonly used units of measure in science. Some of the basic units of the international system are shown in blue:

Name of quantity measuredUnit of measurement nameUnit of measurement symbol
Area |(A)|
Centimetre squared
Metre squared
Hectare
|\text{cm}^2|
|\text{m}^2|
|\text{ha}|
Angle (|\theta|)Degree​​|^{\circ}|
Concentration |(C)|
Gram per litre
Parts per million
Percentage
Mole per litre
|\text{g/L}|
|\text{ppm}|
|\%|
|\text{mol/L}|
Distance |(d)|
Millimetre
Centimetre
Decimetre
Metre
Kilometre
|\text{mm}|
|\text{cm}|
|\text{dm}|
|\color{blue}{\text{m}}|
|\text{km}|
Force |(F)|​Newton​|\text{N}|
Mass |(m)|
Milligram
Gram
Kilogram
Tonne
|\text{mg}|
|\text{g}|
|\color{blue}{\text{kg}}|
|\text{t}|
Density (|\large{\rho}|)Gram per millilitre|\text{g/mL}|
Pressure |(P)|
Pascal
Kilopascal
Atmosphere
Millimetre of mercury
|\text{Pa}|
|\text{kPa}|
|\text{atm}|
|\text{mm Hg}|
Solubility
Gram per litre
Gram per 100 millilitres
|\text{g/L}|
|\text{g/100mL}|
Temperature |(T)|
Degree Celsius
Degree Fahrenheit
Kelvin
|^\circ \text{C}|
|^\circ \text{F}|
|\color{blue}{\text{K}}|
Time |(t)|
Second
Minute
Hour
|\color{blue}{\text{s}}|
|\text{min}|
|\text{h}|
Volume |(V)|
Cubic centimetre
Cubic metre
Millilitre
Litre
|\text{cm}^3|
|\text{m}^3|
|\text{mL}|
|\text{L}|
Find out more!

Main Prefixes

The International System of Units (SI) provides certain prefixes for multiples and submultiples of units of measurement. The symbol for the new units of measurement formed is then composed of two symbols: that of the multiple and that of the unit of measurement :

Prefix Power Symbol
Pico |10^{-12}= 0.000\ 000 000\ 001| |\text{p}|
Nano |10^{-9}= 0.000\ 000 001| |\text{n}|
Micro |10^{-6}= 0.000\ 001| |\mu|
Milli |10^{-3}= 0.001| |\text{m}|
Centi |10^{-2}= 0.01| |\text{c}|
Deci |10^{-1}= 0.1| |\text{d}|
Unit |10^{0}= 1| -
Déca |10^{1}= 10| |\text{da}|
Hecto |10^{2}= 100| |\text{h}|
Kilo |10^{3}= 1000| |\text{k}|
Mega |10^{6}= 1\ 000\ 000| |\text{M}|
Giga |10^{9}= 1\ 000\ 000\ 000| |\text{G}|
Example
  • One kilometre (km) corresponds to 1 000 metres (m).
  • One centilitre (cL) corresponds to 0.01 litre (L).