tonneforce

The tonne-force (tf) is a non-SI unit of force defined as the force exerted by a mass of one tonne under standard gravity. By definition, 1 tonne-force equals 1000 kilograms times 9.80665 meters per second squared, or 9806.65 newtons. In practical terms, it is commonly expressed as about 9.81 kilonewtons, and it equals roughly 2,204.62 pounds-force.

Because it is not part of the International System of Units (SI), the tonne-force is used primarily in engineering contexts to describe force magnitudes corresponding to masses measured in tonnes. It appears in specifications for lifting capacities, hydraulic cylinders, presses, and cranes, among other equipment. In modern practice, engineers are encouraged to use newtons or kilonewtons where possible, to avoid ambiguity.

The value of a tonne-force depends on gravity; the standard tonne-force uses standard gravity (9.80665 m/s^2) at sea level, so local gravity variations can shift the exact force value. Because gravity can vary by location and over time, some definitions of tonne-force may be presented with an explicit gravity assumption or expressed in terms of kilograms-force.

The term can be confused with short ton-force or long ton-force in some regions, so it is important to specify that metric tonne is intended and which gravity standard is applied. In contexts requiring precision, the SI units of force (newtons or kilonewtons) are preferred.