Newtons to Pounds-force (N to lbf)

1 newton equals 0.2248089431 pounds-force (rounded).

How to convert newtons to pounds-force

To convert newtons to pounds-force, multiply the number of newtons by 0.2248089431. The factor is rounded to 10 significant digits. To go the other way, multiply pounds-force by 4.448221615 (rounded).

pounds-force = newtons × 0.2248089431

Example: 10 newtons = 2.248089431 pounds-force.

About these units

Newton (N)

Metric (SI)Current unit

The SI unit of force: the force that accelerates one kilogram by one meter per second squared. About the weight of a small apple.

Isaac Newton gave his name to the unit for his second law of motion, force equals mass times acceleration. Metric engineers needed a force unit that fitted the metre-kilogram-second system, and the CGPM standardized one in 1946; the 9th CGPM in 1948 adopted the name newton, with symbol N. Before that, many metric users measured force in kilograms-force, which confuses weight with mass, and CGS users had the much smaller dyne.

One newton is the force that gives a one-kilogram mass an acceleration of one meter per second every second. For scale, a 200-gram apple weighs about 1.96 N on Earth, so a newton is roughly the weight of a small apple. It equals 100,000 dynes and about 0.225 pound-force. Forces in the thousands are written in kilonewtons. Because the newton is built directly from kilograms, meters and seconds, it slots into formulas for pressure, energy and power without any conversion constants.

The newton is the reference unit for force on this site.

Sources: Wikipedia: Newton (unit); BIPM: 9th CGPM (1948), Resolution 7; Wikipedia: Centimetre-gram-second system of units

Pound-force (lbf)

US & ImperialCurrent unit

Exactly 4.4482216152605 newtons: the weight of a one-pound mass under standard gravity. The US unit of force.

People have used the pound-force since the eighteenth century for low-precision work, long before anyone needed to define it carefully. A pound of material on Earth's surface pulls with about a pound of force, which made it convenient to treat the two as one. The twentieth century demanded a precise definition: one pound-force is the avoirdupois pound, exactly 0.45359237 kg, multiplied by standard gravity of 9.80665 meters per second squared, which comes to about 4.448 newtons.

Because the unit is not simply mass times acceleration in its own system, formulas in English engineering units need a conversion constant of about 32.174 pound-feet per pound-force second squared. A slug, 32.174049 pounds of mass, is what one pound-force accelerates at one foot per second squared. In the US, jet and rocket thrust is often given as pounds of thrust: each Space Shuttle solid rocket booster produced 3,300,000 pounds-force. Earth's gravity varies by up to about half a percent between equator and pole, which low-precision work can ignore.

1 pound-force = 4.448221615 newtons (approximately).

Sources: Wikipedia: Pound (force); NIST Guide to the SI, Appendix B.8: conversion factors

Related conversions

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