<P> For materials that change in volume with water content, such as coal, the water content, u, is expressed in terms of the mass of water per unit mass of the moist specimen: </P> <Dl> <Dd> u ′ = m wet − m dry m wet (\ displaystyle u' = (\ frac (m_ (\ text (wet)) - m_ (\ text (dry))) (m_ (\ text (wet))))) </Dd> </Dl> <Dd> u ′ = m wet − m dry m wet (\ displaystyle u' = (\ frac (m_ (\ text (wet)) - m_ (\ text (dry))) (m_ (\ text (wet))))) </Dd> <P> However, geotechnics requires the moisture content to be expressed with respect to the sample's dry weight (often as a percentage, i.e.% moisture content = u × 100%) </P>

Water content of soil can be greater than 100