Pounds-force to Kilonewtons (lbf to kN)

1 pound-force equals 0.004448221615 kilonewtons (rounded).

How to convert pounds-force to kilonewtons

To convert pounds-force to kilonewtons, multiply the number of pounds-force by 0.004448221615. The factor is rounded to 10 significant digits. To go the other way, multiply kilonewtons by 224.8089431 (rounded).

kilonewtons = pounds-force × 0.004448221615

Example: 10 pounds-force = 0.04448221615 kilonewtons.

About these 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

Kilonewton (kN)

Metric (SI)Current unit

1,000 newtons. Used for structural loads, climbing gear ratings and engine thrust.

Kilonewtons exist because the newton is small. The prefix kilo- dates to the 1795 French decimal system and means one thousand, and attaching it to the newton, which the CGPM named in 1948, gives a unit sized for the loads that engineers actually handle. A kilonewton is 1,000 newtons.

One kilonewton is the weight of roughly 102 kilograms at standard gravity, or about 510 of the 200-gram apples that make a handy picture of a single newton. Structural engineers quote building and bridge loads this way, and rocket and jet engine makers quote thrust in kilonewtons and meganewtons. Each Space Shuttle solid rocket booster produced 3,300,000 pounds-force, or 14.7 meganewtons, which is 14,700 kilonewtons. Strengths of ropes, anchors and climbing hardware are also commonly given in the unit.

1 kilonewton = 1,000 newtons (exactly).

Sources: Wikipedia: Newton (unit); Wikipedia: Metric prefix; Wikipedia: Pound (force)

Related conversions

See all force units.