International System of Units — the standard in science and engineering.
Centimetre-Gram-Second system, commonly used in physics and chemistry.
Gravitational metric units based on standard gravity (g = 9.80665 m/s²).
Imperial and US customary force units used in engineering and industry.
Force Conversion Guide
Newton & SI Force Units
The newton (N) is the SI unit of force, defined as the force required to accelerate 1 kilogram at 1 m/s². Engineering practice commonly uses the kilonewton (kN = 1000 N) for structural loads and the meganewton (MN = 10⁶ N) for large-scale civil and aerospace applications.
Kilogram-force & Metric Gravitational Units
The kilogram-force (kgf) is defined as the force exerted by 1 kg of mass under standard gravity (g = 9.80665 m/s²). Widely used in mechanical engineering, material testing, and everyday contexts. 1 kgf = 9.80665 N. The tonne-force (tf) equals 1000 kgf ≈ 9.806 kN.
Pound-force, Kip & Imperial Units
The pound-force (lbf) is the force exerted by 1 pound-mass under standard gravity. 1 lbf ≈ 4.44822 N. The kilopound-force (kipf) = 1000 lbf is the standard unit for structural engineering in the US. Short ton-force = 2000 lbf; long ton-force = 2240 lbf.
Dyne & CGS Units
The dyne (dyn) is the CGS unit of force: 1 dyn = 10⁻⁵ N. It is frequently encountered in surface tension measurements (dyn/cm), electromagnetism (Gaussian units), and classical physics literature.
Key Conversion Factors
| Unit | = Newtons (N) |
|---|---|
| 1 N | 1 N (base) |
| 1 mN | 0.001 N |
| 1 kN | 1,000 N |
| 1 MN | 1,000,000 N |
| 1 dyn | 0.00001 N |
| 1 gf | 0.00980665 N |
| 1 kgf | 9.80665 N |
| 1 tf | 9,806.65 N |
| 1 ozf | ≈ 0.27801 N |
| 1 lbf | ≈ 4.44822 N |
| 1 kipf | ≈ 4,448.22 N |
| 1 ston-f | ≈ 8,896.44 N |
| 1 lton-f | ≈ 9,964.02 N |
Frequently Asked Questions
What is the difference between mass and force?
Mass is an intrinsic property of matter (kilograms), while force is mass multiplied by acceleration (F = ma). Kilogram-force (kgf) and pound-force (lbf) are gravitational force units derived from mass under standard gravity.
When should I use kN vs kgf in structural engineering?
Modern structural codes (Eurocode, ISO) standardize on kilonewtons (kN). Older references still use kgf. Use the converter to bridge between them: 1 kN ≈ 101.972 kgf.
What is a "kip" and where is it used?
A kip (kipf, klbf) is a kilopound-force equal to 1000 lbf ≈ 4448.22 N. It is the dominant unit in US structural engineering practice (AISC, ACI), where loads and reactions are specified in kips.