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Force

Newtons to kilograms-force

1 N = 0.101972 kgf

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One newton is 0.1019716213 kilograms-force, because one kilogram-force is exactly 9.80665 newtons. The kilogram-force is a metric unit that measures force but is named after a mass, which is precisely the confusion SI was built to eliminate.

About the units

The kilogram-force, also called the kilopond and written kgf or kp, is the gravitational force on one kilogram at standard gravity. It belongs to the older metric gravitational system, which used the kilogram-force alongside the metre and the second and was standard in continental European engineering well into the twentieth century. SI replaced it with the newton, which is defined from mass and acceleration rather than from an assumed gravitational field. The kilogram-force is now deprecated but far from extinct — it survives in older machinery, in some Asian markets and in colloquial use where people say a spring pulls with so many kilos.

The exact factor

The value is exactly 9.80665 N per kgf, since standard gravity was fixed at that figure by the third General Conference on Weights and Measures in 1901. It is a defined constant rather than a measurement: actual gravity varies from about 9.78 at the equator to 9.83 at the poles, so a kilogram-force is not quite the same real force in Stockholm as in Singapore. That variation is around half a per cent, which is negligible for a bathroom scale and not negligible in precision force measurement.

Where you meet this conversion

Older European technical documentation, particularly German, Italian and Nordic machinery manuals from before the 1980s. Spring specifications, clamping forces and cable ratings in legacy equipment are given in kilopond. Bicycle and gym equipment sometimes quotes resistance in kilograms, meaning kilograms-force. In Japan and South Korea the unit persists in some industrial contexts. Anyone commissioning or repairing older machinery meets it, and treating a kilopond figure as newtons understates the force nearly tenfold.

Common values

Value (N) Converted (kgf)
1 0.101972
2 0.203943
5 0.509858
10 1.01972
25 2.54929
50 5.09858
100 10.1972
500 50.9858
1 000 101.972

Values are rounded for reading. The converter above keeps full precision.

The other way around

1 kgf = 9.80665 N

Kilograms-force to newtons multiplies by 9.80665. The approximation of 10 is high by two per cent and perfectly adequate for anything that is not a design calculation — 50 kgf is roughly 500 N, against the true 490.

Value (kgf) Converted (N)
1 9.80665
2 19.6133
5 49.0332
10 98.0665
25 245.166
50 490.332
100 980.665
500 4 903.32
1 000 9 806.65

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