Force Converter
Convert between newtons, pound-force, and other force units.
About the Force Converter
The Force Converter turns a force written in newtons into pound-force, and back again. Those are the two units engineering drawings, spring ratings and load specifications are written in, and mixing them up by a factor of four and a half is a common and expensive mistake. Type a number, pick the direction, and the answer updates as you type.
How to convert newtons to pound-force
One pound-force is 4.448222 N. The figure is not arbitrary: a pound-force is defined as the weight of one pound of mass under standard gravity, so it is 0.45359237 kg × 9.80665 m/s², which works out at 4.4482216 N.
Worked example. A spring rated at 500 N pulls with 500 ÷ 4.448222 = 112.4 lbf. Going the other way, a 75 lbf clamping force is 75 × 4.448222 = 333.6 N.
Newtons to pound-force conversion table
| Newtons (N) | Pound-force (lbf) |
|---|---|
| 1 | 0.2248089 |
| 2 | 0.4496178 |
| 3 | 0.6744268 |
| 5 | 1.124045 |
| 10 | 2.248089 |
| 20 | 4.496178 |
| 50 | 11.24045 |
| 100 | 22.48089 |
| 250 | 56.20223 |
| 500 | 112.4045 |
| 1,000 | 224.8089 |
Pound-force is not the same as pound
A pound (lb) measures mass. A pound-force (lbf) measures force. They happen to carry the same number in standard gravity, which is exactly why they are so often confused. A 10 lb mass weighs 10 lbf on Earth, but in orbit it still has 10 lb of mass and weighs nothing at all. Torque figures, bolt ratings and winch capacities printed as "lb" almost always mean pound-force.
Real-world values
- A 1 kg object resting on Earth presses down with 9.807 N, or 2.205 lbf.
- An adult of 70 kg weighs 686.5 N, which is 154.3 lbf.
- A typical bicycle brake lever is squeezed with about 100 N, or 22.5 lbf.
- A car seat belt is tested to roughly 27,000 N, which is 6,070 lbf.
- One Rolls-Royce Trent 1000 engine produces up to 360,000 N of thrust, or 81,000 lbf.
- A Falcon 9 first stage lifts off with 7,600,000 N of thrust, which is 1,710,000 lbf.
What is a newton?
The newton is the SI unit of force, named after Isaac Newton and defined by his second law: one newton accelerates one kilogram at one metre per second squared. In base units it is kg·m/s². A convenient everyday check is that a small apple, around 100 g, weighs about 1 N on Earth — which is roughly where the story about the apple earns its keep.
Units this converter supports
Two: newton (N) and pound-force (lbf). Both directions are available, so this page also serves as a pound-force to newton converter. Other force units, such as kilogram-force, dyne and kip, are not offered.
Frequently asked questions
How many newtons is one pound-force?
4.448222 N. A pound-force is defined as the weight of one pound of mass under standard gravity, so it is 0.45359237 kg multiplied by 9.80665 m/s², which gives 4.4482216 N before rounding.
What is a newton?
The newton is the SI unit of force: the force that gives a mass of one kilogram an acceleration of one metre per second squared. In base units it is kg·m/s². A 1 kg object at rest on Earth presses down with about 9.81 N.
Is a pound-force the same as a pound?
No. A pound (lb) is a unit of mass and a pound-force (lbf) is a unit of force. They have the same number only in standard gravity. Engineering drawings and torque figures usually mean pound-force even when they print lb.
Which units does this converter support?
Two: newton (N) and pound-force (lbf). Both directions are available, so you can also read it as a pound-force to newton converter.
Related converters
- Mass Converter — kilograms, pounds, stones and tons.
- Acceleration Converter — m/s², g-force and ft/s².
- Pressure Converter — pascals, bar, psi, atm and torr.