Decimetre ($\mathrm{dm}$)

A decimetre, symbol $\mathrm{dm}$, is exactly one tenth of a metre:The SI prefix deci fixes the factor $10^{-1}$. This exact relation concerns units; the uncertainty of a measured length still depends on the measurement.^[ref]

The decimetre connects familiar lengths to volume particularly neatly. A cube with edges $1\mathrm{dm}$ has volumeThus a litre is exactly a cubic decimetre, while a cubic metre contains 1,000 litres. The exponent acts on the conversion factor as well as the unit: a cubic decimetre is not one tenth of a cubic metre.^[ref]

For example, a rectangular container measuring $2\mathrm{dm}$ by $3\mathrm{dm}$ by $0.5\mathrm{dm}$ has volume $3\mathrm{d}{\mathrm{m}}^3=3\mathrm{L}$, assuming the stated dimensions describe its interior. A length conversion becomes a cubic conversion when used to compute volume.