Moment of Inertia Converter — kg·m², lb·ft², g·cm²
Convert between 6 units of moment of inertia — kg·m², kg·cm², g·cm², lb·ft², lb·in², and oz·in². Moment of inertia measures resistance to rotational acceleration (I = mr²). A hollow cylinder is harder to spin than a solid one of the same mass. Used in electric motor sizing, flywheel energy storage, robotic joint design and vehicle dynamics.
About the Moment of Inertia Converter
Moment of inertia (also called rotational inertia) measures how difficult it is to change the rotational speed of an object — the rotational equivalent of mass in linear motion. It depends on both the mass and how that mass is distributed relative to the rotation axis. The SI unit is kg·m². Engineers use it in flywheel design, motor selection, gear systems, and any application involving rotating machinery.
- ›A solid cylinder's moment of inertia = ½mr² — hollow cylinders are harder to spin for the same mass
- ›Figure skaters pull in their arms to reduce moment of inertia and spin faster (conservation of angular momentum)
- ›Flywheels in energy storage systems are designed with high moment of inertia to store more rotational energy
- ›Moment of inertia × angular acceleration = torque (the rotational analogue of F = ma)
kg·m² to lb·ft² — Conversion Table
| kg·m² (kg·m²) | lb·ft² (lb·ft²) |
|---|---|
| 1 kg·m² | 23.7304 lb·ft² |
| 2 kg·m² | 47.4608 lb·ft² |
| 5 kg·m² | 118.652 lb·ft² |
| 10 kg·m² | 237.304 lb·ft² |
| 20 kg·m² | 474.608 lb·ft² |
| 50 kg·m² | 1,186.521 lb·ft² |
| 100 kg·m² | 2,373.042 lb·ft² |
| 1,000 kg·m² | 23,730.422 lb·ft² |
Last updated: August 17, 2026 · Calculated using SI-validated constants (NIST)
Frequently Asked Questions
What units does the Moment of Inertia Converter — kg·m², lb·ft², g·cm² support?
The Moment of Inertia Converter — kg·m², lb·ft², g·cm² supports multiple units with instant conversion. Convert between 6 units of moment of inertia — kg·m², kg·cm², g·cm², lb·ft², lb·in², and oz·in². Moment of inertia measures resistance to rotational acceleration (I = mr²). A hollow cylinder is harder to spin than a solid one of the same mass. Used in electric motor sizing, flywheel energy storage, robotic joint design and vehicle dynamics. All results use SI-validated constants accurate to 8 significant figures.
Is this Moment of Inertia Converter — kg·m², lb·ft², g·cm² free?
Yes — completely free. No registration, no limits. Works on all devices including mobile.
How accurate is this converter?
Accurate to 8 significant figures using precise mathematical constants validated against international SI standards (NIST and ISO 80000).