Pound-force (lbf)

Definition

The force of one pound under standard gravity, exactly 4.4482216152605 N.

History

The pound-force is the weight of one pound of mass under standard gravity, a natural force unit in the imperial system. It equals about 4.448 newtons.

Where it is used

Pounds-force are used in US engineering and to quote thrust, such as a rocket engine rating.

Typical uses include US engineering, thrust ratings.

Conversion pages

These pages convert pound-force to or from another unit in force.

• Newton to pound-force

Other Force units

• Newton (N)
• Kilogram-force (kgf)
• Kilonewton (kN)

Sources

• NIST SP 811 NIST SP 811, App. B (force). lbf and kgf are exact via the pound/kilogram and standard gravity 9.80665 m/s² (CGPM 1901); SP 811 prints them rounded · Dataset reviewed Nov 11, 2026