The unit kilogram-force (kgf, often just kg) or kilopond (kp) is defined as the force exerted by Earth's gravity on one kilogram of mass. Although the gravitational pull of the Earth varies as a function of position on earth, it's here defined as exactly 9.80665 m/s². So one kilogram-force is by definition equal to 9.80665 newtons. The kilogram-force has never been a part of the International System of Units (SI), which was introduced in 1960. The SI unit of force is the newton. Prior to… (More on Kilogram-force)