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Force Converter
Convert a force between SI newtons and the gravitational and older units still found in manuals, such as kilogram-force and pound-force. Standard gravity is stated so the result can be checked.
The newton and standard gravity
A newton is the force that gives a mass of one kilogram an acceleration of one metre per second squared. The gravitational units are built on standard gravity, g = 9.80665 m/s², a value fixed by convention in 1901 and used ever since. It is close to, but not exactly, the actual gravity at any particular place.
- 1 kgf = 9.80665 N exactly
- 1 lbf = 0.45359237 kg × 9.80665 m/s² = 4.4482216152605 N
- 1 poundal = 1 lb·ft/s² = 0.138254954376 N
- 1 dyne = 10−5 N (the CGS unit)
- 1 kN = 1,000 N, which is about 101.97 kgf
Pounds and kilograms: mass or force?
The pound and the kilogram are units of mass, while pound-force and kilogram-force are units of force. They are linked: a one-kilogram mass is pulled with a force of 1 kgf under standard gravity. This is why a person of 70 kg mass presses on the floor with a force of about 686.5 N (70 × 9.80665).
In a loose sense people say "70 kilos" when they mean the weight, which is harmless in daily life. In engineering, writing lbf or kgf rather than lb or kg removes the ambiguity. Use the weight converter if you want mass only.
Rough sizes for orientation
| Force | Approximately |
|---|---|
| 1 N | weight of a small apple, about 102 g |
| 10 N | about 1.02 kgf or 2.25 lbf |
| 1 kN | about 101.97 kgf or 224.8 lbf |
Ratings on ropes, hooks and straps are often stated in kN or kgf. Never use a converted figure to override a manufacturer's marked working load limit.
Common mistakes
- Mixing up force and torque. Torque is force times distance, measured in newton-metres or pound-feet, and is not converted here.
- Using 10 for g without saying so. Rounding 9.80665 to 10 gives a 2% error, which can matter in safety work.
- Treating poundals as pound-force. A poundal is about 1/32 of a pound-force.
For quick estimates, 1 kgf is about 9.8 N and 1 lbf about 4.45 N. A newton is roughly 0.2248 lbf.
Typical uses are reading load ratings on climbing and lifting gear, comparing thrust figures for motors and rockets, converting spring and gauge specifications, and handling older engineering texts that quote kilogram-force. Where a safety margin is involved, work from the manufacturer's stated unit and apply the converted figure only as a cross-check.
Worked example
A rope is rated to hold 10 kilograms-force. What is that in newtons?
Inputs
| Value | 10 |
|---|---|
| From | Kilograms-force (kgf) |
| To | Newtons (N) |
Result
10 kgf = 98.0665 N
| Kilonewtons (kN) | 0.0980665 |
|---|---|
| Meganewtons (MN) | 0.0000980665 |
| Grams-force (gf) | 10,000 |
| Pounds-force (lbf) | 22.046226 |
| Ounces-force (ozf) | 352.739619 |
| Poundals (pdl) | 709.316353 |
| Dynes (dyn) | 9,806,650 |
- Factors are exact definitions where one exists; results are shown to about six significant digits.
Accuracy note: Factors use the standard definitions stated on this page. Results are rounded for display; for engineering or legal work use the full-precision factors.
Frequently asked questions
How many newtons are in a kilogram-force?
One kilogram-force equals exactly 9.80665 newtons, because it is defined as the force of standard gravity on one kilogram of mass.
How many newtons are in a pound-force?
One pound-force is 4.4482216152605 newtons, found by multiplying the pound mass in kilograms by standard gravity.
Is a kilogram a unit of force?
No, the kilogram measures mass. The kilogram-force is a separate unit equal to the force exerted on one kilogram by standard gravity.
What is a dyne?
A dyne is the CGS unit of force: 10^-5 newtons, or the force that gives one gram an acceleration of one centimetre per second squared.
Does the converter depend on where I am on Earth?
No. It uses standard gravity of 9.80665 m/s² by definition, not the local value, so results are the same everywhere.