Pounds to Kilograms (lbs to kg)
One pound is exactly 0.45359237 kg, so multiply pounds by 0.4536. 1,000 lb is 453.6 kg. Dividing by 2.2 runs about 0.2% high, which matters on air waybills and customs papers near a weight limit.
1 lb = 0.45 kg
kilograms (kg)
Quick reference
How to convert pounds to kilograms
To convert pounds to kilograms, multiply by the conversion factor:
Multiply pounds by 0.45359237 to get kilograms. That factor is the legal definition of the pound, so it is exact. Dividing by 2.2 is a handy estimate but runs about 0.2% high, which matters on export paperwork near a weight limit.
| Pounds | Kilograms |
|---|---|
| 100 lb | 45.36 kg |
| 500 lb | 226.80 kg |
| 1,000 lb | 453.59 kg |
| 2,000 lb (US short ton) | 907.18 kg |
| 2,500 lb | 1,133.98 kg |
| 10,000 lb | 4,535.92 kg |
| 20,000 lb | 9,071.85 kg |
| 40,000 lb | 18,143.69 kg |
| 80,000 lb (US federal gross limit) | 36,287.39 kg |
Exact since 1959 — and why ÷2.2 isn't quite right
The international pound has been defined as exactly 0.45359237 kg since the 1959 agreement between the US, UK and Commonwealth countries — so this conversion is exact by definition, not approximate. The popular mental shortcut of dividing by 2.2 implies 0.4545 kg per pound, about 0.2% high; harmless for a quick estimate, but on a 40,000 lb load it overstates the weight by about 38 kg.
Use the exact factor anywhere the number is checked against a limit or a document: customs entries, air waybills, and anything near a weight cutoff.
Where pounds meet kilograms in a real shipment
US domestic freight lives in pounds — LTL quotes, scale tickets, the 80,000 lb federal gross vehicle limit (36,287 kg). The moment cargo goes international, the paperwork flips to kilograms: air waybills, ocean bills of lading and customs declarations all want kg. A 2,500 lb pallet becomes 1,133.98 kg on the export docs.
Getting this wrong in the flattering direction is expensive: understate kilograms on an air waybill and the shipment gets re-weighed and re-rated at the airline's numbers, often with a correction fee on top.
Frequently asked questions
What is 1 lb in kg exactly?
0.45359237 kg, the exact international definition of the pound. Multiplying by 0.45 gets you within about 1%.
How many kg is 80,000 lb?
36,287.39 kg. 80,000 lb is the US federal gross weight limit for a truck on the Interstate, counting the truck itself.
How many kg is 40,000 lb?
18,143.69 kg. Dividing by 2.2 would give 18,181.82 kg, about 38 kg too high.
What is the difference between a metric ton, a short ton and a long ton?
A metric ton (tonne) is 1,000 kg, or 2,204.62 lb. A US short ton is 2,000 lb (907.18 kg), and a UK long ton is 2,240 lb (1,016.05 kg). Freight papers outside the US almost always mean the metric ton.