What this does
Converts pounds to kilograms as you type. The pound is defined as exactly 0.45359237 kg, so kg = lb × 0.45359237. The page starts with 1 pound entered, which the tool displays as 0.453592 kg — the definition has eight decimals but results are rounded to six. Type in either field and the other updates on every keystroke; the ⇄ button swaps the units while keeping the number on the left. It runs entirely in the browser, so it works at a check-in desk with no signal.
Pounds to kilograms at a glance
| Pounds | Kilograms | Context |
|---|---|---|
| 1 | 0.453592 | a pound of butter is 454 g |
| 7.5 | 3.401943 | 7 lb 8 oz, a typical newborn |
| 10 | 4.535924 | a bag of potatoes |
| 50 | 22.679619 | US checked-bag limit |
| 70 | 31.751466 | the heavier "overweight" tier |
| 150 | 68.038856 | a common adult weight |
| 200 | 90.718474 | another |
| 2,000 | 907.18474 | a US short ton |
How do I estimate pounds to kilograms in my head?
Halve it, then knock off a tenth of the result. 180 lb → 90 → 81 kg (real 81.6). 30 lb → 15 → 13.5 kg (real 13.6). For small amounts just halve and round down a little: a 5 lb bag is "a bit over 2 kg". The rule works because 0.4536 is 0.5 minus about nine percent.
Is 50 lb the same as the 23 kg airline limit?
Not quite. 50 lb is 22.679619 kg, so a bag packed to the US limit is 320 g under a 23 kg allowance — while 23 kg is 50.7 lb. Airlines that quote both usually round in your favour, but a scale abroad reads only kilograms, so pack to 22.5 kg if you want margin. Worked example of the tool's rounding: 50 × 0.45359237 = 22.6796185 exactly, and the seventh decimal 5 rounds the display up to 22.679619.
How do I convert pounds and ounces, like 7 lb 8 oz?
Turn the ounces into a decimal pound first — there are 16 ounces in a pound, so divide by 16. 7 lb 8 oz is 7.5 lb, which converts to 3.401943 kg; 6 lb 11 oz is 6.6875 lb, which is 3.033399 kg. Birth weights are the classic case, since US hospitals record lb and oz while most of the world charts grams. The Ounces unit is also in the dropdowns on this page if you'd rather convert the ounces separately.
Why do medical forms and shipping labels want kilograms?
Drug doses are calculated per kilogram of body weight everywhere, including in the US, so a clinic will convert your 165 lb to 74.842741 kg before working out a mg/kg dose. International couriers and airlines price in kilograms too, and they round up to the next whole unit or half-unit: a parcel weighing 20.1 lb is 9.117 kg and bills as 9.5 or 10 kg. Knowing the metric figure before you pack can drop you a tier.
What about stone?
UK body weight is often "12 stone 7", where a stone is 14 pounds. Convert to pounds first (12 × 14 + 7 = 175 lb = 79.378665 kg) or pick Stone directly in the left dropdown — the category tabs are hidden on this page, but every weight unit (milligrams through metric tons, ounces, pounds, stone) is still available. For the reverse direction with luggage and gym-plate references, see kg to lbs; the full converter covers everything else.