What the force converter does
A force converter changes a push or pull from one unit to another. This one covers the SI newton and kilonewton, the imperial pound-force, the kilogram-force still seen on older gauges and specifications, and the CGS dyne. Enter a value, choose both units, press Convert, and the result goes through the newton with exact factors.
Results show up to 8 decimal places with trailing zeros dropped. Converting a single dyne into kilonewtons gives 0.00000001 kN, right at that limit, so anything smaller rounds to 0.
Exact conversion factors
| Unit | Symbol | In newtons |
|---|---|---|
| Newton | N | 1 |
| Kilonewton | kN | 1,000 |
| Pound-force | lbf | 4.4482216152605 |
| Kilogram-force | kgf | 9.80665 |
| Dyne | dyn | 0.00001 |
Where the factors come from
The newton is the SI unit of force: the force that accelerates a 1 kg mass at 1 m/s². It's defined in the BIPM SI Brochure as kg·m/s².
The kilogram-force is what a 1 kg mass weighs under standard gravity, a conventional value of exactly 9.80665 m/s² adopted by the General Conference on Weights and Measures in 1901. Real gravity is a little weaker at the equator and a little stronger at the poles, but the unit always uses the standard figure.
The pound-force follows the same idea with the pound: 0.45359237 kg × 9.80665 m/s² = 4.4482216152605 N, exactly. NIST Special Publication 811 lists this factor.
The dyne is one gram times one centimeter per second squared, or 10⁻⁵ N. You'll mostly meet it in older physics texts and in surface tension values quoted in dyn/cm.
Quick reference
| From | To | Multiply by |
|---|---|---|
| pound-force | newtons | 4.44822 |
| newtons | pound-force | 0.224809 |
| kilogram-force | newtons | 9.80665 |
| newtons | kilogram-force | 0.101972 |
| kilonewtons | pound-force | 224.809 |
| kilonewtons | kilogram-force | 101.972 |
| kilogram-force | pound-force | 2.20462 |
That last row is the same number as kilograms to pounds, because both force units are built from their mass unit times the same standard gravity.
Worked examples
- The weight of a 75 kg person in newtons: 75 kgf × 9.80665 = 735.49875 N.
- A climbing carabiner rated at 24 kN: 24 × 224.8089431 = about 5,395 lbf, or 24 × 101.9716213 ≈ 2,447 kgf.
- A 100 lbf pull in kilogram-force: 100 × 4.4482216152605 ÷ 9.80665 = 45.359237 kgf.
- One pound-force in dynes: 444,822.16 dyn.
Mass vs force
The most common mistake with these units is mixing up mass and force. A load "rated at 500 kg" on a shelf or hoist usually means 500 kgf, the weight of 500 kg of material, which is about 4.9 kN. If a structural calculation asks for a load in kN, convert the kilogram-force figure here. If you have a plain mass in kilograms or pounds and want another mass unit, use the weight converter instead.
Related converters and calculators
- Weight converter: kilograms, pounds, ounces and tonnes.
- Pressure converter: force spread over an area, in Pa, bar and psi.
- Energy converter: joules, the work done by a newton over a meter.
- Beam calculator: sizes a reinforced concrete beam for a given span and load.
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