Kilonewton (kN) can be converted into kilograms (kg) by first multiplying the value of kN by 1000 and then dividing it by earth's gravity, which is denoted by "g" and is equal to 9.80665 meter per second.
A kilonewton is equal to 1000 newtons. Newton, denoted by "N", is the unit of force used by the International System of Units (SI units) and is named after Sir Isaac Newton to honor his contributions in the field of classical mechanics. Kilogram is the base unit of mass used by the SI units. Since kN is a measure of force and kg is a measure of mass, they are not equivalent and can't be used interchangeably. So converting kN to kg should only be done for the sake of convenience, and either one of them can't be used as the equivalent of the other when they're part of an equation. Instead, kN can be converted into kilogram-force (kgf), which is a unit of force that is less frequently used. By definition, 1 kilogram-force is equal to the force exerted by a mass of 1 kg placed in earth's gravity. This means that 1 kilogram-force is equal to 9.80665 kilogram-meter per second per second, or 9.80665 N.