Newton (N)

The newton is the SI unit of force, named after Sir Isaac Newton. One newton is the force needed to accelerate one kilogram of mass at the rate of one meter per second squared.

Pound-force (lbf)

A pound-force is the force exerted by Earth's gravitational field on a mass of one pound. 1 lbf ≈ 4.448 N.

Kilogram-force (kgf)

A kilogram-force is the force exerted by Earth's standard gravity on one kilogram of mass. 1 kgf ≈ 9.807 N.

Dyne (dyn)

The dyne is the CGS unit of force. One dyne is the force required to accelerate a mass of one gram at a rate of one centimeter per second squared. 1 dyn = 10⁻⁵ N.

Poundal (pdl)

A poundal is the force needed to accelerate one pound-mass at a rate of one foot per second squared. 1 pdl ≈ 0.138 N.

Historical Context

Before the standardization of the SI system, various regional and industry-specific force units were common. The gravitational units (kgf, gf) are still widely used in some fields despite not being SI units because they relate directly to the weight of objects in Earth's gravity.

Practical Applications

Different force units are preferred in different contexts:

• Newtons are used in scientific calculations, engineering, and physics
• Pound-force is common in U.S. engineering and construction
• Kilogram-force is used in many non-scientific applications worldwide
• Meganewtons (MN) are used for large forces like rocket thrust