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Convert lbs to kg
Convert pound (lb) to kilogram (kg) instantly. Free, no signup, nothing is uploaded — everything runs in your browser.
Pound to Kilogram conversion table
| Pound [lb] | Kilogram [kg] |
|---|---|
| 0.01 | 0.00453592 |
| 0.1 | 0.04535924 |
| 1 | 0.45359237 |
| 2 | 0.90718474 |
| 3 | 1.36077711 |
| 5 | 2.26796185 |
| 10 | 4.5359237 |
| 20 | 9.0718474 |
| 50 | 22.6796185 |
| 100 | 45.359237 |
| 1,000 | 453.59237 |
How to convert pound to kilogram
kg = lbs × 0.453592
Example: 150 lb = 150 × 0.453592 = 68.0389 kg
To convert back (kilogram to pound): lbs = kg ÷ 0.453592
What is a pound?
A pound (lb) is a unit of mass in the US customary and imperial systems, defined as exactly 0.45359237 kilograms.
What is a kilogram?
A kilogram (kg) is the base unit of mass in SI. The standard unit for body weight, food packaging, and most mass measurements worldwide.
When do you need to convert pound to kilogram?
Medical dosing is the highest-stakes lb → kg conversion. Many drug dosages are calculated in mg per kg of body weight, so a 180 lb patient (81.65 kg) and a 200 lb patient (90.72 kg) get meaningfully different doses. Doctors, nurses, and pharmacists convert at the point of care; an off-by-5% conversion can mean a wrong dose for a weight-sensitive drug.
International shipping rates are calculated on kilograms, even when the package is weighed on a pound scale at a US post office. USPS, FedEx, and UPS all convert to kg for international labels. A 5 lb package to London shows as 2.27 kg on the international waybill, and the rate is calculated on the kg value.
Fitness and body-composition apps increasingly use kg. A user logging 175 lb of bodyweight in an app that stores in kg will see 79.38 kg. Apps like Strong, Hevy, and most European strength-training apps require kg input. Powerlifters and Olympic lifters almost always train in kg, and their competition plates are kg (the 20 kg, 15 kg, 10 kg, 5 kg, 2.5 kg set is standard worldwide).
Frequently asked questions
What is 1 lb in kg?
1 lb = 0.4536 kg, by exact international definition. For most purposes, multiplying pounds by 0.4536 is accurate to 4 decimal places; the full exact value is 0.45359237 kg per lb.
How many pounds is 1 kg?
1 kg = 2.20462 lb. The reverse of the above, and a useful sanity check: 1 kg should be slightly more than 2 lb (a 1-kg bag of sugar is just over 2 lb), and 2.20462 is correct.
Why do US doctors and patients use different units?
Because of a 1975 metrication push that failed in the US. Most US hospitals now report patient weight in kg (required by Joint Commission since 1985 for medication dosing), but patients still know their weight in lb. So a 70 kg patient is told "you weigh 154 lb" and converts back mentally every time. The clinical record is in kg; the conversation is in lb.
How accurate is the lb → kg conversion?
Exact. 1 lb = 0.45359237 kg by international agreement, no rounding. So 1 lb × 0.45359237 = 0.45359237 kg, full stop. The only "error" is from truncating to fewer decimal places; 0.4536 kg (4 sig figs) is off by 0.002% from the true value.