Convert pounds to kilograms
Pounds to kilograms with the exact 0.45359237 factor. Accepts stone-and-pound entries like 11 st 4 lb and converts pasted columns.
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kilograms = pounds × 0.45359237 = 150 × 0.45359237 = 68.039 kg 1 lb = 0.453592 kg
| pounds | kilograms | Stone and pounds |
|---|---|---|
| 1 lb | 0.454 kg | 0 st 1.0 lb |
| 10 lb | 4.536 kg | 0 st 10.0 lb |
| 20 lb | 9.072 kg | 1 st 6.0 lb |
| 50 lb | 22.680 kg | 3 st 8.0 lb |
| 100 lb | 45.359 kg | 7 st 2.0 lb |
| 110 lb | 49.895 kg | 7 st 12.0 lb |
| 120 lb | 54.431 kg | 8 st 8.0 lb |
| 130 lb | 58.967 kg | 9 st 4.0 lb |
| 140 lb | 63.503 kg | 10 st 0.0 lb |
| 150 lb | 68.039 kg | 10 st 10.0 lb |
| 160 lb | 72.575 kg | 11 st 6.0 lb |
| 170 lb | 77.111 kg | 12 st 2.0 lb |
| 180 lb | 81.647 kg | 12 st 12.0 lb |
| 200 lb | 90.718 kg | 14 st 4.0 lb |
| 220 lb | 99.790 kg | 15 st 10.0 lb |
| 250 lb | 113.398 kg | 17 st 12.0 lb |
| 300 lb | 136.078 kg | 21 st 6.0 lb |
Multiply by 0.45359237
Pounds to kilograms is the easy direction, because the factor is the definition: one avoirdupois pound is exactly 0.45359237 kg. Nothing about that number was measured. It was agreed by six countries in 1959 and has not moved since.
Halving is the mental shortcut — 150 lb is roughly 75 kg — and it is 10% high. Halve, then knock off a tenth: 75 minus 7.5 is 67.5, against a true 68.04. Close enough for a suitcase.
Entering stone and pounds
British weights arrive as two numbers. Type 11 st 4 lb and it is read as 158 lb
and converted to 71.67 kg. You can also type plain pounds, or decimal stone, and the page tells
you which interpretation it used. The stone-and-pounds readout below the result restates your
entry, so a transposed digit is visible immediately.
Reference points
| Pounds | Kilograms | Stone and pounds |
|---|---|---|
| 100 | 45.36 | 7 st 2 lb |
| 120 | 54.43 | 8 st 8 lb |
| 140 | 63.50 | 10 st 0 lb |
| 150 | 68.04 | 10 st 10 lb |
| 160 | 72.57 | 11 st 6 lb |
| 180 | 81.65 | 12 st 12 lb |
| 200 | 90.72 | 14 st 4 lb |
| 250 | 113.40 | 17 st 12 lb |
Medicine runs on kilograms
Paediatric and anaesthetic dosing is per kilogram, which is why hospitals record weight in kilograms even in countries that weigh themselves in pounds. Converting a pound figure and rounding it before dosing is a known source of error, and the standard mitigation is to weigh in kilograms directly rather than to convert. If you are entering a weight into a medical form, use the unconverted measurement wherever you can.
Baggage, shipping and the tonne
A 50 lb US baggage limit is 22.68 kg — slightly under the 23 kg used almost everywhere else. For freight, note that a metric tonne is 1,000 kg (2,204.6 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). Three units, one word, a 12% spread — always check which ton a quote means.
Not the troy pound
Precious metals use troy weight, where a pound is 12 troy ounces and 373.24 g, not 453.59 g. If your figure came from a bullion dealer rather than a bathroom scale, this page is the wrong tool.
Questions
How many kg is 1 lb?
Exactly 0.45359237 kg. This is a definition agreed internationally in 1959, so nothing about it is approximate.
Can I enter stone and pounds?
Yes. Type 11 st 4 lb and it is read as 158 lb, then converted. The page shows you how it interpreted the entry so a typo cannot hide.
What is a healthy conversion habit for gym plates?
Remember 45 lb is 20.41 kg and 25 lb is 11.34 kg — imperial and metric plates are close but never identical, so a "matched" bar loaded from both sets is slightly asymmetric.
Why do airlines quote 23 kg rather than 50 lb?
23 kg is 50.7 lb, so the metric allowance is very slightly more generous. Bags are weighed in whichever unit the airport scale uses; the difference matters only at the margin.