A cubic megametre (American spelling: cubic megameter) (symbol Mm³) is an SI derived unit of volume. It is the volume of a cube with edges 1 megametre (10⁶ m) in length.

1 Mm³ = 10¹⁸ cubic metres

• 1 Mm³ is the volume of the Pacific Ocean
• the total volume of all oceans on Earth is 1.37 Mm³
• the volume of Earth is 1083.2 Mm³

See 1 E18 m³ for a comparison with other volumes.

cubic kilometre << cubic megametre