How to use the Force Converter
- Enter the force value you have.
- Select its unit and the unit you need.
- Confirm your figure is a force, not a mass — kilograms-force and kilograms are different quantities.
- Use newtons or kilonewtons for any structural or physics calculation.
- For rotational force use the torque converter, which works in newton-metres.
How the calculation works
The newton is the SI unit: the force that accelerates one kilogram at one metre per second squared. Everything converts through it. The kilonewton dominates structural engineering because typical building loads land conveniently in the tens to hundreds of kN, keeping numbers readable on a drawing.
Gravitational units — kilograms-force and pounds-force — express force as the weight of a given mass under standard gravity, fixed at 9.80665 m/s². One kilogram-force is therefore 9.80665 N and one pound-force is 4.44822 N. They persist in mechanical and materials specifications because a load cell reading in kgf is directly comparable to a mass on a scale, which is intuitive on a shop floor even though it conflates two distinct quantities.
The mass–force distinction is where errors originate. A 70 kg person has a mass of 70 kg and a weight of about 686 N on Earth. Beam and fixing calculations require the force, so multiply mass by g before using it. Conversely, a bolt rated for 10 kN does not support 10,000 kg — it supports about 1,020 kg under Earth gravity, and less again once a safety factor is applied.
force_target = (F_source × N_per_source) ÷ N_per_target; 1 kgf = 9.80665 N; 1 lbf = 4.4482216 N; 1 dyne = 10⁻⁵ N; F = m × g with g = 9.80665 m/s²Source: BIPM SI Brochure 9th edition; ISO 80000-4; CGPM 3rd meeting (1901) standard gravity.
Worked example
A shelf bracket is rated 45 kgf per fixing and you need the value in kilonewtons for a load schedule.
- Enter 45 and select kilograms-force.
- Convert to newtons: 45 × 9.80665 = 441.3 N.
- Convert to kilonewtons: 0.441 kN per fixing.
- Four fixings give 1.77 kN, or about 180 kg of supported mass before any safety factor.
45 kgf is 0.441 kN — a set of four brackets carries 1.77 kN, which should then be derated by the specified safety factor.
Frequently asked questions
How many newtons is one pound-force?+
4.44822 N. Conversely, one newton is about 0.225 lbf, roughly the weight of a small apple.
Is a kilogram a unit of force?+
No, it is mass. The kilogram-force is the corresponding force under standard gravity, equal to 9.80665 N.
What does kN mean on structural drawings?+
Kilonewtons — thousands of newtons. A 10 kN load corresponds to about 1,020 kg of mass under Earth gravity.
Does gravity vary enough to matter?+
Local gravity ranges from about 9.78 to 9.83 m/s². Standard gravity of 9.80665 is used for all definitions, and the variation is negligible outside precision metrology.
Last reviewed September 1, 2026. We review this page whenever the underlying formula, tax year, published rate or standard changes.