A kilogram-force (kgf) is a unit of force that will accelerate 1 kilogram of mass at 9.80665 m/s2, the standard acceleration due to gravity on Earth's surface (referred to as gn). The kilogram-force is often referred to as the kilopond (kp).[note 1]
Since a newton is defined as the force that will accelerate 1 kilogram of mass at 1 m/s2, and acceleration is proportional to force, one kilogram-force is therefore equal to 9.80665 newtons. It is also equal to 2.20462 pounds-force.
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)[note 1]
- 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)[note 2]
- 1 kgf ≈ 70.93164 poundal (symbol: pdl)
- Another name for a kilogram-force. Not to be confused with "kilopounds", meaning 1,000 pounds of mass.
- A non-SI unit of force equal to 1,000 pound-force.
- The International System of Units (SI), NIST Special Publication 330, 2008 Edition (pdf page 57 of 77 pdf pages)
- Glossary From the website of NASA's Goddard Space Flight Center.
- The International System of Units (SI), NIST Special Publication 330, 2008 Edition (pdf page 30 of 77 pdf pages)
- Metric Conversion Table Scroll down to "Force"
- Resolution of the 3rd meeting of the CGPM (1901)
- Resolution 12 of the 11th meeting of the CGPM (1960)