m⁴
meter to the fourth
Area moment of inertiaexact by definition
The metre to the fourth power is the coherent SI unit of second moment of area, the purely geometric property that sets a section's bending stiffness. Its factor is 1 by construction. It is far too large for practical sections, since a steel beam's second moment of area is measured in units of 10⁻⁶ m⁴ or smaller.
Watch out: This quantity is often called the moment of inertia and written \(I\), the same name and symbol as the mass moment of inertia in kg·m². They are unrelated: this one contains no mass and appears in \(\delta = PL^3/(3EI)\) and \(\sigma = Mc/I\), while the mass version appears in \(\tau = I\alpha\).
| 1 m⁴ | 1,000,000,000,000 mm⁴ |
Solvers that use area moment of inertia