kg·m²
kilogram square meter
Moment of inertiaexact by definition
The kilogram square metre is the SI unit of mass moment of inertia, the rotational analogue of mass. Its factor is 1 by construction and the unit is exact. It measures how strongly a body resists angular acceleration about a given axis, and it depends on the axis chosen as well as on the body.
Watch out: Mass moment of inertia (kg·m²) is a different quantity from the second moment of area (m⁴) used in beam bending, despite both being called "moment of inertia" and both often written \(I\). One involves mass and governs rotational dynamics, the other involves only geometry and governs stiffness. Their units differ, which is the quickest way to tell which one a formula wants.
| 1 kg·m² | 1 kg·m² |
Solvers that use moment of inertia