Pounds to Kilograms

How pounds ↔ kilograms conversion works

Body weight, shipping weights, and grocery labels often switch between pounds (lb) and kilograms (kg). This converter uses the international avoirdupois pound: 1 lb = 0.45359237 kg exactly. That is the standard factor used in science and everyday trade conversions in most countries that still display pounds alongside metric units.

Formulas

kilograms = pounds × 0.45359237. pounds = kilograms ÷ 0.45359237. Edit either field; the other updates automatically so you can start from the unit printed on a scale, bag tag, or form.

Worked examples

• 150 lb ≈ 68.04 kg — a common adult reference weight on U.S. forms.
• 1 kg ≈ 2.205 lb — useful when a European label lists kilograms only.
• A 25 kg suitcase ≈ 55.12 lb — helpful when airline limits mix units (for example, 50 lb versus 23 kg rules).
• 200 lb ≈ 90.72 kg; 100 kg ≈ 220.46 lb.

Reference table (rounded)

• 50 lb ≈ 22.7 kg
• 100 lb ≈ 45.4 kg
• 180 lb ≈ 81.6 kg
• 10 kg ≈ 22.0 lb
• 70 kg ≈ 154.3 lb

Tips for scales and travel

Bathroom scales and gym plates may round differently from this exact factor. For medical or legal contexts, use the precision your form requires. Airline baggage: convert the limit once, then weigh in the same unit the carrier states on your ticket. Stone (UK, 14 lb) is not handled here — multiply stone by 14 to get pounds, then convert.

How to use it

1. Enter weight in pounds or kilograms.
2. Read the converted value in the other field.
3. Round only when you present the number (labels often use one decimal).

Common mistakes

• Confusing pounds with kilograms on a dual-unit scale (always check the unit indicator).
• Using troy pounds (precious metals) — this page is avoirdupois only.
• Converting a rounded result back and forth, which accumulates display error.

Frequently asked questions

Is 2.2 lb per kg exact enough?

For rough estimates, yes. For shipping declarations and many medical forms, prefer the full factor (0.45359237) and then round once.

Does this convert ounces?

Not by itself. There are 16 avoirdupois ounces in a pound — convert ounces to pounds first (ounces ÷ 16), then use this tool.

Why do fitness apps disagree by a tenth of a kilo?

Most round for display. Small differences usually come from rounding, not from a different definition of the pound.

Limitations

Does not convert ounces alone, stones as a primary unit, or troy pounds used for precious metals. For a broader unit overview, see our metric and imperial conversions guide.