cubic centimeter
VolumeSection modulusexact by definition
The cubic centimetre is 10⁻⁶ cubic metres, exactly one millilitre. It is the unit of engine displacement in motorcycles and small engines, and the "cc" of medicine, where a cubic centimetre and a millilitre are interchangeable by definition.
Watch out: Medical practice has largely abandoned "cc" in favour of mL because cc is easily misread as "u" or as a zero in handwriting. The volumes are identical; the objection is to the abbreviation.
| 1 cm³ (Volume) | 0.001 L |
| 1 cm³ (Section modulus) | 1,000 mm³ |
A cubic centimetre of water at 4 °C weighs almost exactly one gram, which is not a coincidence: the gram was originally defined that way. The definition has since moved to the kilogram and then to the Planck constant, but the near-identity survives and is why water density is a memorable 1.00 g/cm³.
The cubic centimetre is exactly 10⁻⁶ cubic metres, an exact decimal relation. It is the standard unit of section modulus in European and international steel tables, where an IPE 300 beam has an elastic section modulus of about 557 cm³ about its strong axis.