Kilogram-force

A kilogram-force (kgf) is a unit of force which will accelerate 1 kilogram of mass to 9.80665 m/s2, the standard average acceleration due to gravity on Earth's surface (referred to as gn). Since a newton is defined as the force which will accelerate 1 kilogram of mass to 1 m/s2, one  kilogram-force is by definition equal to 9.80665 newtons.

The kilogram-force was not very well defined until the 3rd General Conference on Weights and Measures (Conférence Générale des Poids et Mesures, CGPM) defined gn, the standard gravity, to be 9.80665 m/s2 in 1901. Although it was once widely used, it has never been part of the International System of Units (SI) introduced in 1960 by the 11th GCPM.

The kilogram-force is still used to some extent in a few countries, but it is generally considered to be obsolete in most countries.

Equivalent units of force

 * 1 kgf ≡ 9.80665 newton (symbol: N)
 * 1 kgf ≡ 980,665 dyne (symbol: dyn)
 * 1 kgf ≡ 1 kilopond (symbol: kp)
 * 1 kgf ≡ 9.80665×10-3 sthène (symbol: sn)
 * 1 kgf ≈ 2.20462 pound-force (symbol: lbf)
 * 1 kgf ≈ 2.20462×10-3 kip (symbol: kip)
 * 1 kgf ≈ 70.93164 poundal (symbol: pdl)