A Japanese motorcycle manual specs spring stiffness in kgf/mm. I found a US spring in lbf/in. How do I tell if they're equivalent?

Convert both to SI (N/m) or use this converter to match units. Remember that 1 inch = 25.4 mm, so you'll need both conversions. A 10 lbf/in spring ≈ 45 kgf/cm—not the same as 10 kgf/cm. Also see [converting lbf to kilonewtons]({/force/lbf-to-kn/}) for structural loads.

Why do some countries use kgf instead of newtons?

Historically, engineers used the force of gravity on a known mass (1 kg) as an intuitive standard. It's cleaner than newtons for everyday machinery specs. Modern SI uses newtons, but kgf persists in automotive and industrial contexts.

My pressure gauge reads in 'kgf/cm²' (kilogram-force per square centimeter). Is that the same as atmospheric pressure?

Not quite. Standard atmospheric pressure is 1.033 kgf/cm² (or 1 atm). If your gauge reads 1.0 kgf/cm², you're very close to sea level pressure.

Is kgf the same as kilogram (kg) of weight?

No. A kilogram is mass (1 kg = 1,000 grams). Kilogram-force is the downward pull of that mass at Earth's surface (1 kgf ≈ 9.81 N). They're related by gravity, not the same unit.

Pounds-Force (lbf) to Kilogram-Force (kgf) Converter

Enter a value to instantly convert between force units.

From

Precision4 dp

1 Pound-Force = 0.4536 Kilogram-Force

Key Formulas

Newton → Pound-Force

lbf = N × 0.224809

Pound-Force → Newton

N = lbf × 4.44822

Kilogram-Force → Newton

N = kgf × 9.80665

Newton → Kilogram-Force

kgf = N × 0.101972

Formula

kgf = lbf × 0.453592

Kilogram-force (kgf) is the force exerted by 1 kg at Earth's surface—common in automotive, industrial machinery, and Japanese engineering specs. When US equipment (rated in lbf) must interface with metric machinery (rated in kgf), or when comparing spring constants and clamp forces across markets, this conversion is indispensable.

Source: NIST SP 811, Table B.8

Frequently Asked Questions

Real-World Examples

Definition. 1 lbf is roughly the force of 1 pound mass at Earth's surface—equivalent to 0.454 kgf (the force of 454 grams under gravity).

1 lbf = 0.454 kgf

A Japanese automotive spring spec rates the spring at 100 kgf/cm stiffness. Converting to lbf, that's roughly 220 lbf/cm—useful when ordering compatible US springs.

220 lbf = 100 kgf

An industrial C-clamp rated at 50 lbf clamping force (US spec) equals about 22.7 kgf—a reference when comparing against metric clamps rated in kgf.

50 lbf = 22.68 kgf

A portable luggage scale rated at 10 lbf capacity equals roughly 4.5 kgf—the threshold before it bottoms out.

10 lbf = 4.536 kgf

newtons to lbf lbf to newtons kgf to newtons newtons to kgf kn to newtons newtons to kn

Pounds-Force (lbf) to Kilogram-Force (kgf) Converter

Key Formulas

Formula

Frequently Asked Questions

Real-World Examples

Related Converters