Force Converter
Convert a force between newtons, kilonewtons, pound-force, kilogram-force, kips, tons-force, dynes and poundals all at once, or work out what a mass weighs on Earth, the Moon or Mars.
1 kgf = 9.80665 N · 1 lbf = 4.4482216 N
Absolute vs Gravitational Force Units
Force units come in two families. Absolute units come straight from Newton's second law, force = mass × acceleration. One newton accelerates 1 kg at 1 m/s². The dyne (1 g at 1 cm/s²) and the poundal (1 lb at 1 ft/s²) are built the same way from other base units.
Gravitational units are defined as the weight of a standard mass: the kilogram-force is what 1 kg weighs, and the pound-force is what 1 lb weighs. Real gravity varies from place to place, so in 1901 the CGPM fixed a reference value, standard gravity gₙ = 9.80665 m/s². Together with the international pound (exactly 0.45359237 kg), this makes every factor on this page exact:
The converter changes your value to newtons and then into every other unit, so nothing is lost through a chain of rounded factors. Very small or very large results are shown in scientific notation, so 1 dyn reads 2.24809 × 10⁻⁹ kip rather than rounding to zero.
Weight Is a Force: Why It Changes With Location
Mass is how much matter something contains, and it is the same everywhere. Weight is the force gravity puts on that mass (mass × local gravity), so it changes from place to place. Gravity at Earth's surface ranges from about 9.780 m/s² at the equator to 9.832 m/s² at the poles. A 70 kg person weighs 684.6 N at the equator and 688.2 N at the poles. On the Moon the same person weighs 113.4 N, which is only 11.56 kgf. Enter a mass to try it:
Bathroom and kitchen scales measure force but display mass. They are calibrated for Earth gravity, so the same scale would read about 11.6 kg for a 70 kg person on the Moon. Kgf and lbf always use standard gravity, so "1 kgf" is the same force whether you are in Quito or Oslo.
Worked Example: A 22 kN Carabiner
Climbing carabiners are stamped with their breaking strength in kilonewtons, such as "22 kN" along the spine. What does that mean in kilograms-force and pounds-force?
Step 1: Kilonewtons to newtons
Step 2: Newtons to kilogram-force
Step 3: Newtons to pound-force
The gate-closed rating is about 2,243 kgf or 4,946 lbf. This does not mean you can hang 2.2 tonnes on it. The rating is the static load at which it breaks. A fall produces a much larger force than the climber's weight, and the open-gate and cross-loaded ratings stamped beside it are far lower, often 7 to 10 kN.
Ton-Force: Three Different Units
Hydraulic presses, jacks, punch presses and bolt testers are often rated in "tons", but there are three tons-force, and they differ by up to 12%:
| Unit | Defined as | Newtons | kN |
|---|---|---|---|
| Short tons-force (US) (tonf (US)) | 2,000 lbf | 8,896.443 | 8.896 |
| Tonnes-force (metric) (tf) | 1,000 kgf | 9,806.65 | 9.807 |
| Long tons-force (UK) (tonf (UK)) | 2,240 lbf | 9,964.016 | 9.964 |
A "20-ton" shop press sold in the US is normally rated in short tons: 40,000 lbf, which is 177.9 kN or 18.14 tonnes-force. A European press rated at 20 t gives 196.1 kN, about 10% more. If the spec sheet gives kN, use that figure. It is the only one that can't be read two ways.
Which Force Unit You Will See Where
| Field | Usual units |
|---|---|
| Physics and most engineering outside the US | N, kN, MN |
| US structural engineering (beam and column loads) | kip, lbf |
| Climbing, rigging and lifting gear | kN, with lbf on US gear |
| Rocket and jet engine thrust | kN, lbf |
| Magnet pull force, spring scales, luggage scales | kgf or lbf (often labelled just “kg” or “lb”) |
| Hydraulic presses and jacks | tons-force (short or metric), kN |
| Precision instruments, keyboard switches, stylus pressure | gf, mN, cN |
| Older physics and surface-tension tables | dyn (dyn/cm for surface tension) |
| Old British engineering texts | pdl, tonf (long) |
When a product gives a force in "kg" (a 50 kg magnet, a 100 kg pull-up bar rating), it almost always means kilogram-force. Choose kgf in the converter to get newtons.
Every Unit in Newtons and Pound-Force
Only need pounds and newtons? The lbs to newtons converter has two-way tables and covers the "lbs" ratings on gas struts, fishing line and bows.
| 1 unit | System | Newtons | Pound-force |
|---|---|---|---|
| Newtons (N) 1 kg × 1 m/s² | SI | 1 | 0.224809 |
| Kilonewtons (kN) 1,000 N | SI | 1,000 | 224.808943 |
| Meganewtons (MN) 1,000,000 N | SI | 1,000,000 | 224,808.9431 |
| Millinewtons (mN) 0.001 N | SI | 0.001 | 0.000225 |
| Pound-force (lbf) 0.45359237 kg × 9.80665 m/s² | Gravitational | 4.4482216 | 1 |
| Ounce-force (ozf) 1/16 lbf | Gravitational | 0.2780139 | 0.0625 |
| Kips (kip) 1,000 lbf | Gravitational | 4,448.2216153 | 1,000 |
| Short tons-force (US) (tonf (US)) 2,000 lbf | Gravitational | 8,896.4432305 | 2,000 |
| Long tons-force (UK) (tonf (UK)) 2,240 lbf | Gravitational | 9,964.0164182 | 2,240 |
| Kilogram-force (kgf) 1 kg × 9.80665 m/s² | Gravitational | 9.80665 | 2.204623 |
| Gram-force (gf) 1 g × 9.80665 m/s² | Gravitational | 0.0098067 | 0.002205 |
| Tonnes-force (metric) (tf) 1,000 kgf | Gravitational | 9,806.65 | 2,204.622622 |
| Dynes (dyn) 1 g × 1 cm/s² | CGS | 1 × 10⁻⁵ | 2.24809 × 10⁻⁶ |
| Poundals (pdl) 1 lb × 1 ft/s² | FPS absolute | 0.138255 | 0.031081 |
Frequently asked questions
How many newtons is 1 kg?
A kilogram is a mass, not a force, so strictly it has no value in newtons. Its weight under standard gravity is 9.80665 N, which is exactly 1 kgf. For quick estimates, 1 kg ≈ 10 N.
What does 1 newton feel like?
About the weight of a small apple. A mass of 102 g weighs 1 N under standard gravity. A 1 litre bottle of water weighs roughly 9.8 N.
What is a kip?
A kip (kilo-pound) is 1,000 lbf, or 4.448 kN. US structural engineers use it to keep large loads readable: a 50 kip column load is 50,000 lbf.
Can a force be negative?
Yes. Force has a direction, and a minus sign usually means the opposite direction, for example compression rather than tension in a structural member. The converter keeps the sign.
Is a dyne still used?
Rarely. It is the CGS unit (10⁻⁵ N) and survives mainly in surface tension, where values like 72 dyn/cm for water equal 72 mN/m.
How accurate are the results?
The factors are exact by definition, and results are shown to six significant figures, with scientific notation for very small or very large numbers.
Sources
- NIST Special Publication 811: conversion factors for kgf, lbf, kip, ton-force, dyne and poundal, and standard gravity gₙ = 9.80665 m/s².
- BIPM: The International System of Units (SI Brochure): definition of the newton.
- NASA Planetary Fact Sheet: surface gravity of the Moon and Mars.
Related Tools
Convert BTU per hour to tons of refrigeration.
Convert joules, calories, kilowatt-hours, and more.
Convert liters per minute to other flow rate units.
Convert between hertz, kilohertz, megahertz, and more.
Convert torque from in-lb to ft-lb.
Convert torque from in-lb to N?m.