litres
mL, L, cm3, m3 are all SI units that can be used to measure the volume of water.
1 metric cup = 250 millilitres 1 US legal cup = 240 millilitres
I assume you mean volume rather than capacity. The milliliter would be the best answer. It is 1 thousandth of a liter.
Meters
Metres.
centimetre.
grams
volume
Centimetres
the metric system
The most appropriate measure is a metre.
If the object is irregular the best way is to measure the volume of water it displaces when you immerse it completely in water.