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Free pounds to kg converter with instant bidirectional conversion. Enter pounds to get kilograms, or enter kilograms to get pounds. Includes ounces and stones output for additional weight context.
Last updated: April 16, 2026
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Weight Formulas
kilograms = pounds x 0.45359237 and pounds = kilograms x 2.2046226218
Pounds to Kilograms
100 lb = 45.3592 kg
Formula: 100 x 0.45359237 = 45.3592 kg
Ounces
1,600 oz
Stones
7.1429 st
Quick reference
Formula
lb x 0.45359237
Uses exact conversion factor for accurate kilogram output.
Formula
kg x 2.2046226218
Reverse conversion with precise pound output.
Outputs
oz and st
Useful for fitness, shipping, and personal tracking.
Common use
Gym and nutrition
Convert body weight standards across regions.
Trade use
kg and lb labels
Helpful for international shipping and inventory.
Direction aware
lb to kg or kg to lb
Edit either field to drive conversion direction.
For 100 lb, the equivalent weight is 45.3592 kg.
Input
100 lb
Output
45.3592 kg
This pounds to kg converter uses fixed international conversion factors between imperial and metric mass units. The calculator detects which field you edit and applies the matching conversion formula in real time.
kg = lb x 0.45359237lb = kg x 2.2046226218oz = lb x 16These constants are standard for science, fitness, logistics, and commercial calculations.
Result: 180 lb equals 81.6466 kg
This is also 2880 ounces or 12.8571 stones.
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