Force converter

Convert kgf to newtons, lbf to N and kN to kgf or lbf, using standard gravity (9.80665 m/s²) and the exact pound-force of 4.4482216152605 N.

Drafted with AI writing toolsUpdated Checked examples: 4

A number in the “from” unit, or with its own unit
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Converted value
N
Converted value: 9.80665 N
Significant figures: 12; Nearest, ties away from zero
Conversion
1 kgf = 9.80665 N
Conversion factor
9.80665
Exactness
Exact

1 kgf is exactly 9.80665 N.

The same amount counted in each unit

kgf1 kgfN9.80665 N
1 kgf in every Force unit Rows: 7
UnitValueDefinition
newton (N)9.80665Base unit
kilonewton (kN)0.009806651 kN = 1,000 N, exact
dyne (dyn)980,6651 dyn = 0.00001 N, exact
pound-force (lbf)2.2046231 lbf = 4.4482216152605 N, exact
kilogram-force (kgf)11 kgf = 9.80665 N, exact
ounce-force (ozf)35.273961 ozf = 0.27801385095378125 N, exact
poundal (pdl)70.931641 pdl = 0.138254954376 N, exact
How it's calculated S
  1. Convert kilogram-force to newton

    1 kgf×9.80665 Nkgf=9.80665 N1\ \text{kgf} \times 9.80665\ \tfrac{\text{N}}{\text{kgf}} = 9.80665\ \text{N}

    1 kgf = 9.80665 N, exact

    Both units are defined exactly and the converted mathematical value has a terminating decimal. A displayed result may still be rounded.

About the force converter

Every force unit is a fixed number of newtons, and one newton accelerates 1 kg at 1 m/s². The gravitational units use standard gravity, g₀ = 9.80665 m/s², set by the 3rd CGPM in 1901: a kilogram-force is 9.80665 N and a pound-force is 0.45359237 kg × 9.80665 m/s² = 4.4482216152605 N, both exact.

The default converts 1 kgf to 9.80665 N. Loads marked in kilograms-force or tonnes-force and climbing or lifting gear rated in kilonewtons are the usual reasons to convert: 1 kN is 101.97 kgf or 224.81 lbf.

A kilogram measures mass and a newton force. Under standard gravity, the weight of 1 kg is approximately 9.81 N. Near sea level, gravity runs from about 9.78 m/s² at the equator to 9.83 m/s² at the poles, a spread of about 0.5%.

How to convert kg to newtons (kgf to N)

Multiply kilograms-force by 9.80665, the standard acceleration of gravity in m/s²: 1 kgf = 9.80665 N, so a 50 kg load weighs 490.33 N. That is what "kg to newtons" means in practice: the weight of a mass under standard gravity. Divide newtons by 9.80665 to go back.

The kilogram-force is defined with standard gravity, g₀ = 9.80665 m/s², fixed by the 3rd CGPM in 1901 (NIST SP 811, Appendix B.9). Real gravity runs from about 9.78 m/s² at the equator to 9.83 m/s² at the poles.

How to convert newtons to pounds-force

Multiply newtons by 0.224809, or divide by 4.4482216152605. A pound-force is the weight of one pound (0.45359237 kg) under standard gravity, so 1 lbf = 4.4482216152605 N exactly. A 200 lbf load is 889.64 N.

kN to kgf, lbf and tonnes

Climbing and lifting gear is rated in kilonewtons. 1 kN = 101.97 kgf = 224.81 lbf, so a carabiner marked 22 kN is rated to 2,243 kgf or 4,946 lbf.

A tonne-force is 1,000 kgf, which is 9.80665 kN. Divide kN by 9.80665 to get tonnes-force: 10 kN is about 1.02 tonnes-force.

Weight, mass and force

A kilogram measures mass and a newton measures force. Weight is mass times gravitational acceleration, F = m × g: a 70 kg person weighs 686.47 N under standard gravity, which is 70 kgf or 154.32 lbf.

One newton accelerates 1 kg at 1 m/s². Under standard gravity it is the weight of 101.97 g, so 1 N is 0.101972 kgf.

Kilogram-force and pound-force build standard gravity into the unit. That is why 1 lbf is exactly 0.45359237 kgf, the same ratio as the pound to the kilogram.

Dynes, ounce-force and poundals

  • Dyne: 10⁻⁵ N, the CGS force that accelerates 1 g at 1 cm/s².
  • Ounce-force: 1/16 lbf, or 0.27801385 N.
  • Poundal: the force that accelerates 1 lb at 1 ft/s², 0.138254954376 N. A pound-force is 32.174 poundals, the value of standard gravity in ft/s².

Force conversion chart

Repeating decimals are rounded to six places.

ValueFromToConverted force
1kgfN9.80665
1lbfN4.448222
1kNkgf101.971621
1Ndyn100000
16ozflbf1
1pdlN0.138255

Common mistakes

  • Using a mass as a force. 70 kg is a mass; 70 kgf is a force of 686.47 N.
  • Rounding g to 9.81 or 10. 9.81 is 0.03% high and 10 is 2% high; kgf and lbf are defined with 9.80665.
  • Mixing up lb and lbf. A pound (lb) is mass; a pound-force (lbf) is that mass's standard weight.
  • Confusing pound-force with poundal. They differ by a factor of 32.174.

For mass in kilograms, pounds or stones, use the weight converter. The F = ma calculator finds force from mass and acceleration, and the torque converter handles a force acting on a lever arm.

Worked examples

1 kgf in newtons

Value
1 kgf
From
kilogram-force (kgf)
To
newton (N)
Converted value
9.80665 N

Checked against: 1 kgf = 1 kg × 9.80665 m/s² (standard gravity, CGPM 1901)

1 lbf in newtons

Value
1 lbf
From
pound-force (lbf)
To
newton (N)
Converted value
4.44822161526 N
Exactness
Exact

Checked against: 0.45359237 kg × 9.80665 m/s² = 4.4482216152605 N (NIST SP 811 App. B)

1 kN in lbf

Value
1 kN
From
kilonewton (kN)
To
pound-force (lbf)
Converted value
224.8089431 lbf

Checked against: 1000 / 4.4482216152605

1 N in dynes

Value
1 N
From
newton (N)
To
dyne (dyn)
Converted value
100,000 dyn

Checked against: 1 dyn = 10⁻⁵ N (NIST SP 811 App. B)

Questions

How many newtons are in a kilogram?

A mass of 1 kg weighs 9.80665 N under standard gravity, which is the definition of 1 kilogram-force. The kilogram measures mass and the newton force, so the conversion needs an acceleration; 9.80665 m/s² is the conventional value fixed in 1901, and near sea level local gravity differs from it by up to about 0.3%.

How do I convert lbf to newtons?

Multiply by 4.4482216152605, usually rounded to 4.448. One pound-force is the weight of one pound (0.45359237 kg) under standard gravity, so the factor is exact. A 200 lbf load is 889.64 N, and 1 N is 0.224809 lbf.

How many kgf is 1 kN?

Approximately 101.97 kgf. Multiply kilonewtons by approximately 101.9716, or divide by 0.00980665, to get kilograms-force. A carabiner marked 22 kN is rated to 2,243 kgf, or 4,946 lbf, and a 5 kN anchor to 510 kgf. The displayed multiplier and results are rounded; the underlying conversion is exact because the kilogram-force is defined with standard gravity, 9.80665 m/s².

What is the difference between a pound and a pound-force?

A pound (lb) is mass, 0.45359237 kg; a pound-force (lbf) is the weight of that mass under standard gravity, 4.4482216152605 N. On Earth a 10 lb object weighs about 10 lbf, which is why everyday speech uses one word for both. The poundal, 0.138255 N, is the force that accelerates 1 lb at 1 ft/s².

How many newtons does a person weigh?

A 70 kg person weighs 686.47 N under standard gravity (70 × 9.80665), which is 70 kgf or 154.3 lbf. Force-based bathroom scales measure this force and divide by g to display kilograms, so near sea level a scale set up for standard gravity reads about 0.3% low at the equator and 0.3% high at the poles.

About this calculator

xto=xfrom×ffromftof=one unit expressed in N\begin{gathered} x_{\text{to}} = x_{\text{from}} \times \dfrac{f_{\text{from}}}{f_{\text{to}}} \\ f = \text{one unit expressed in } \text{N} \end{gathered}

Sources

  1. NIST SP 811 (2008), Guide for the Use of the SI, Appendix B — conversion factors
  2. NIST Handbook 44, Appendix C — General tables of units of measurement

Checked against references

This calculator includes 4 worked examples with independently sourced answers. They run in the test suite, and you can run them here too.

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