Metric system

The metric system is the most widely used system of measurement in the world. It is based on a simple idea: that all measurements can be expressed as multiples or fractions of basic units based on the number ten. This property makes the system easy to use and consistent across length, area, volume and mass.

 

 

Length units in relation to the metre

The most common units that are smaller and larger than one metre are shown here. The table shows the factor, name and symbol for each unit.

 

 

Smaller than one metre

Factor	Name	Symbol
\( \large 10^{-1} \)	decimetre	dm
\( \large 10^{-2} \)	centimetre	cm
\( \large 10^{-3} \)	millimetre	mm
\( \large 10^{-6} \)	micrometre	µm
\( \large 10^{-9} \)	nanometre	nm
\( \large 10^{-12} \)	picometre	pm
\( \large 10^{-15} \)	femtometre	fm
\( \large 10^{-18} \)	attometre	am
\( \large 10^{-21} \)	zeptometre	zm
\( \large 10^{-24} \)	yoctometre	ym

 

 

Larger than one metre

Factor	Name	Symbol
\( \large 10^{1} \)	decametre	dam
\( \large 10^{2} \)	hectometre	hm
\( \large 10^{3} \)	kilometre	km
\( \large 10^{6} \)	megametre	Mm
\( \large 10^{9} \)	gigametre	Gm
\( \large 10^{12} \)	terametre	Tm
\( \large 10^{15} \)	petametre	Pm
\( \large 10^{18} \)	exametre	Em
\( \large 10^{21} \)	zettametre	Zm
\( \large 10^{24} \)	yottametre	Ym

 

 

The metric system makes it possible to compare and convert between all measurements using simple factors of ten. It is precisely this simplicity that makes the system universal and easy to learn.