The kilogram-force (kgf) is a unit of force defined as the force exerted by one kilogram of mass in a gravitational field of standard gravity (9.80665 m/s²). It is not an SI unit but is often used in engineering contexts. The exact definition is 1 kgf = 9.80665 N (newtons).
The concept of kilogram-force originated in the 19th century as engineers needed a practical way to express forces in terms of mass. The term became common in engineering and physics discussions, especially before the widespread adoption of the SI system.
Kilogram-force is commonly used in engineering and physics to express loads and forces, especially in mechanical and civil engineering. It is also used in some regions, such as parts of Europe and Asia, where traditional metric units are still prevalent.