lb⋅ft2\text{lb}{\cdot}\text{ft}^{2}

pound square foot

Moment of inertiaexact by definition

The pound square foot is one pound of mass at one foot of radius of gyration, exactly 0.0421401100938048 kg·m². The value is exact because the pound and the foot are exactly defined. It is the customary unit for flywheel and rotating machinery inertia.

Watch out: Older machinery literature quotes flywheel effect as WR² or WK² in lb·ft², which is the same quantity as mass moment of inertia. Some sources however use the slug foot squared, which is 32.174 times larger. Check which mass unit the value assumes before using it in a torque calculation.

1 lb⋅ft2\text{lb}{\cdot}\text{ft}^{2} 0.04214011 kg⋅m2\text{kg}{\cdot}\text{m}^{2}

One pound square foot in every moment of inertia unit

421,401gram square centimeter (g·cm²)
42,140.1kilogram square millimeter (kg·mm²)
2,304ounce square inch (oz·in²)
421.401kilogram square centimeter (kg·cm²)
144pound square inch (lb·in²)
42.1401gram square meter (g·m²)
1pound square foot (lb·ft²)this unit
0.372971pound-force inch second squared (lbf·in·s²)
0.0421401kilogram square meter (kg·m²)
0.031081slug square foot (slug·ft²)
0.031081pound-force foot second squared (lbf·ft·s²)
0.0000421401tonne square meter (t·m²)