Force Converter
Convert force between newtons, kilonewtons, pounds-force, kips, kilogram-force, ounces-force, poundals and dynes using exact factors.
Updated Formula covered by automated tests
Force ratings appear on climbing gear, lifting slings, load cells, bolts, springs and structural drawings, and they rarely agree on units. European equipment is stamped in kilonewtons, American engineering drawings use pounds-force and kips, older metric gauges read in kilogram-force, and physics textbooks from the CGS era use dynes. This converter takes a force in any of those units and lists it in all of them.
The most frequent source of confusion is the habit of quoting forces in mass units, as in "the rope holds 2000 kilos". A kilogram is a mass; the matching force unit is the kilogram-force, the weight of one kilogram under standard gravity. Keeping the two apart is what this page is for, and every factor here is exact, derived from the defined pound (0.45359237 kg) and standard gravity (9.80665 m/s²).
The formula
- F
- Force, in newtons (N)
- m
- Mass being accelerated, in kilograms
- a
- Acceleration, in meters per second squared
- 9.80665 m/s²
- Standard acceleration of gravity, the conventional value used to define gravitational force units
- kip
- Kilopound, 1000 lbf, used in US structural engineering
Newton’s second law says force equals mass times acceleration, and the SI builds its force unit directly from it: one newton accelerates one kilogram at one meter per second squared. Gravitational units such as the pound-force and kilogram-force instead define force as the weight of a standard mass, which ties them to a chosen value of gravity. The value 9.80665 m/s² was adopted by the General Conference on Weights and Measures in 1901, so these units are fixed multiples of the newton even though real gravity varies from place to place.
The poundal and the dyne are the "absolute" units of the foot-pound-second and centimeter-gram-second systems: one poundal accelerates one pound at one foot per second squared, and one dyne accelerates one gram at one centimeter per second squared (10⁻⁵ N). They are rare today but still appear in older literature on surface tension and ballistics.
Worked example
Sam is checking a climbing carabiner stamped "22 kN" on its spine and wants to explain to a friend in the US what that means in pounds-force and in the kilogram figures people often quote.
- 1 Convert kilonewtons to newtons: 22 × 1000 = 22,000 N.
- 2 Divide by the pound-force: 22,000 ÷ 4.4482216 = 4945.8 lbf, or about 4.95 kip.
- 3 Divide by the kilogram-force: 22,000 ÷ 9.80665 = 2243.4 kgf.
Result: The carabiner’s rated strength is about 4950 lbf, equal to the weight of roughly 2243 kg at rest. In a fall, forces come from deceleration rather than static weight, which is why gear is rated in force units and not in kilograms.
Before you rely on the result
- Gravitational units assume standard gravity. If you need the actual weight of an object at a specific location, multiply its mass by the local value of g instead.
- Rated strengths on equipment are tested under specific conditions; converting units does not tell you a safe working load, which usually includes a safety factor set by the relevant standard.
Frequently asked questions
Can I just multiply kilograms by 10 to get newtons?
For a quick estimate, yes; the exact factor for kilogram-force is 9.80665, so the shortcut overstates by about 2 percent. For anything safety-related, use the exact value or, better, the newton figure printed on the equipment.
Why do bathroom scales show kilograms if they measure force?
A scale measures the force your body presses down with, then divides by an assumed gravity to display mass. Because gravity is about 0.5 percent stronger at the poles than at the equator, a spring scale calibrated in one place reads slightly differently in another.
What is the difference between lb and lbf?
The pound (lb) is a mass of exactly 0.45359237 kg. The pound-force (lbf) is the weight of that mass under standard gravity, 4.4482216152605 N. In everyday US usage both are written "lb", so context tells you which one is meant.
How strong is a 1 kip load in metric terms?
One kip is 1000 lbf, which is 4448.22 N, or about 4.45 kN. Structural engineers in the US often quote beam loads and bolt capacities in kips.