pound (lb)
1 pound = 0.45359237 kilograms
What is pound?
A pound is a unit of mass in imperial and US customary systems equal to 16 ounces. It is widely used in the United States for body weight, grocery shopping, and general weight measurement.
Notes: Imperial/USCS unit
Real-world uses
Pounds are the primary unit of weight in everyday American life—used for body weight, grocery items, luggage limits, and newborn birth weights. In the UK, pounds remain common for body weight despite official metrication.
History
The pound descends from the Roman "libra pondo" (a pound by weight), which is why its abbreviation is "lb." The avoirdupois pound was standardized internationally in 1959 as exactly 0.45359237 kilograms.
Common mistakes
Confusing pounds-mass (lb) with pounds-force (lbf), which are technically different quantities. Also, assuming the pound symbol "£" relates to weight—it actually denotes British currency, though both derive from "libra."
When is this conversion used?
Converting between pound and kilogram is common when working across metric and imperial systems, such as international trade, travel between countries with different measurement standards, or following instructions from a different region. Body weight, grocery items, and luggage limits are commonly expressed in kilograms in most countries and pounds in the US and UK, making this one of the most frequently needed mass conversions.
How to convert pound to kilogram
To convert pound to kilogram, multiply the value by 0.45359237.
Conversion formula (from base unit)
x * 0.45359237
Measurement standards
The kilogram is defined by fixing the Planck constant to exactly 6.62607015 × 10⁻³⁴ joule-seconds, as established at the 26th General Conference on Weights and Measures in 2018. This ended the last SI definition based on a physical artefact.
Did you know?
The International Prototype of the Kilogram, a platinum-iridium cylinder stored near Paris since 1889, was found to have drifted by about 50 micrograms relative to its copies over a century — roughly the mass of a fingerprint.
| pounds | kilograms |
|---|---|
| 0.1 | 0.04535924 |
| 0.5 | 0.22679619 |
| 1 | 0.45359237 |
| 2 | 0.90718474 |
| 5 | 2.26796185 |
| 10 | 4.5359237 |
| 25 | 11.33980925 |
| 50 | 22.6796185 |
| 100 | 45.359237 |
| 250 | 113.3980925 |
| 500 | 226.796185 |
| 1,000 | 453.59237 |
Common values
| pounds | kilograms | |
|---|---|---|
| A paperclip | 0.00220462 pounds | 0.001 kilograms |
| A smartphone | 0.38580896 pounds | 0.175 kilograms |
| A bag of sugar | 2.20462262 pounds | 1 kilogram |
| Average adult human | 154.32358353 pounds | 70 kilograms |
| A small car | 2,645.54714622 pounds | 1,200 kilograms |
Full pound conversion table
| Unit | Value | Factor |
|---|---|---|
| kilogram | 1 lb = 0.45359237 kg | × 0.45359237 |
| gram | 1 lb = 453.59237 g | × 453.59237 |
| ounce | 1 lb = 16 oz | × 16 |
| tonne | 1 lb = 0.00045359 t | × 0.00045359 |
| milligram | 1 lb = 453,592.37 mg | × 453,592.37 |
| microgram | 1 lb = 453,592,370 µg | × 453,592,370 |
| stone | 1 lb = 0.07142857 st | × 0.07142857 |
| short ton (US) | 1 lb = 0.0005 short ton | × 0.0005 |
| long ton (UK) | 1 lb = 0.00044643 long ton | × 0.00044643 |