Defined mass and length units
Mass Moment of Inertia Unit Converter
Convert one non-negative mass moment of inertia about a stated axis. This page does not convert area/second moment of area, which has length-to-the-fourth units.
Converted mass moment
Quantity and dimensions
This scalar expression is for mass moment about a stated axis; r⊥ is perpendicular distance to that axis. For rigid rotation about a fixed axis, τ=Jα is the scoped scalar relation. The parallel-axis theorem is J=JCM+md² for parallel axes.
Implemented factors to kg·m²
| Source unit | Фактор | Основа |
|---|---|---|
| кг·м² | 1 | SI basis |
| кг·см² | 0.0001 | (0.01 m)² |
| г·см² | 0.0000001 | 0.001 kg × (0.01 m)² |
| lbm·ft² | 0.0421401100938048 | 0.45359237 kg × (0.3048 m)² |
| lbm·in² | 0.0002926396534292 | 0.45359237 kg × (0.0254 m)² |
| oz(avdp)·in² | 0.000018289978339325 | (0.45359237/16) kg × (0.0254 m)² |
| охлюв·фут² | 1.3558179483314004 | 4.4482216152605 N × 0.3048 m × s² |
NIST SP 811 Appendix B states how derived factors are formed and gives the defining component conversions. International foot/inch, avoirdupois pound/ounce and standard gravity are used; no U.S. survey foot is used.
ISO status and boundary
ISO 80000-4:2019, edition 2, is Published and covers names, symbols, definitions and units for mechanics. Amendment 1:2025 is Published. ISO/AWI 80000-4, planned edition 3, entered development on 2 July 2026 and is intended to replace the 2019 edition. Exact entries, symbols and amendment wording remain NEEDS_LICENSED_SOURCE; the conversion factors here are derived from unit definitions, not claimed as an ISO table.
Common uniform-body formulas (reference only)
| Uniform solid disk/cylinder, symmetry axis | J=mr²/2 |
| Uniform thick cylindrical annulus, symmetry axis | J=m(r₁²+r₂²)/2 |
| Uniform solid sphere, diameter | J=2mr²/5 |
| Uniform slender rod, transverse center axis | J=mL²/12 |
| Uniform slender rod, transverse end axis | J=mL²/3 |
Real components require the actual mass distribution and axis. Mass moment alone does not determine static unbalance or centrifugal force; those require the first mass moment/eccentricity and speed.
