Pounds-Force to Newtons

Pounds-force and newtons

A pound-force is the weight of one pound under standard gravity: exactly 4.4482216152605 newtons. US engineering, rocket thrust and spring and load ratings use pounds-force (lbf).

The newton is the SI unit of force: the force that accelerates one kilogram at one meter per second squared. Physics, engineering, load ratings and climbing gear (in kN) use newtons.

Worked example

Convert 50 lbf: 50 × 4.448221615 = 222.4110808, so 50 pounds-force is 222.4110808 newtons. Likewise 20 lbf = 88.96443231 N.

Estimating in your head

Multiply by 4.4 for a quick figure; it is off by about 1.1%. For 50 lbf that gives 220 N, against 222.411 exactly.

Going the other way

To convert newtons to pounds-force, divide by 4.448221615 (or multiply by 0.2248089431). The swap button between the boxes opens that page.

N = lbf × 4.448221615

1 lbf = ≈ 4.448221615 N and 1 N = 1 N, both by definition, so the factor is their ratio: 4.448221615 (rounded here; the page uses the full value). Results drop binary floating-point noise beyond 15 significant digits and display at the precision you choose (6 significant figures by default). Copy result copies the full value.