10 lb = 4.5359 kg
Roughly a small package. Multiply 10 lb by 0.45359237. The result is 4.5359 kg.
Fast answers, clean math
Lbs to kg converter
Enter pounds and get kilograms instantly. This page also shows the formula so you can sanity-check the result.
Unit converter
Convert pounds to kilograms
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Formula
How to convert pound to kilogram (lb → kg)
One pound equals exactly 0.45359237 kilograms. This is an exact definition, not an approximation, so the factor never changes.
Formula: kilograms = pounds × 0.45359237
To go the other way, multiply by 2.2046226218: pounds = kilograms × 2.2046226218.
For example, 10 lb × 0.45359237 = 4.5359 kg.
| Pound (lb) | Kilogram (kg) |
|---|---|
| 1 lb | 0.4536 kg |
| 2 lb | 0.9072 kg |
| 5 lb | 2.268 kg |
| 10 lb | 4.5359 kg |
| 20 lb | 9.0718 kg |
| 50 lb | 22.6796 kg |
| 100 lb | 45.3592 kg |
| 150 lb | 68.0389 kg |
| 200 lb | 90.7185 kg |
| 250 lb | 113.3981 kg |
Step by step
Worked pound to kilogram examples
50 lb = 22.6796 kg
Roughly a checked bag. Multiply 50 lb by 0.45359237. The result is 22.6796 kg.
150 lb = 68.0389 kg
Roughly an adult body weight. Multiply 150 lb by 0.45359237. The result is 68.0389 kg.
Background
What is a pound?
A pound is an imperial and US customary unit of mass defined as exactly 0.45359237 kilograms. It is divided into 16 ounces.
The pound traces back to the Roman libra, which is why its symbol is lb. The exact metric value was set by the international yard and pound agreement in 1959.
Everyday scale: A pound is about the weight of a loaf of bread or a can of soup. A US gallon of water weighs roughly 8.3 pounds.
System: imperial / US customary.
Background
What is a kilogram?
The kilogram is the base unit of mass in the SI system. Since 2019 it has been defined using the fixed value of the Planck constant rather than a physical metal cylinder.
For 130 years the kilogram was defined by a platinum-iridium cylinder kept near Paris. In 2019 it was redefined in terms of fundamental constants so it no longer depends on a single object.
Everyday scale: A kilogram is about the mass of a liter of water, a standard bag of sugar, or a typical laptop.
System: metric (SI).
Where it helps
When you need to convert pound to kilogram
Travel and shipping
Airlines, postal services, and couriers set weight limits in kilograms or pounds depending on the region. Converting before you pack or ship avoids overweight fees and rejected parcels.
Cooking and baking
Recipes from different countries list ingredients in grams or ounces. Converting accurately matters most in baking, where ratios of flour, sugar, and butter change the result.
Health and fitness
Body weight, dosages, and nutrition labels mix metric and imperial units. Converting keeps tracking consistent whether your scale, app, or doctor uses kilograms or pounds.
Accuracy
Precision and common mistakes
The pound to kilogram factor is exact by definition, so any error comes from rounding too early. Keep full precision through your calculation and round only the final answer to the precision your task needs.
A common mistake is rounding the conversion factor to two or three digits before multiplying, which can shift the result noticeably on large values. Multiply first, then round. Always keep the unit label with the number so the meaning is never lost.
| Use case | Good rounding |
|---|---|
| Body weight and luggage | 1 decimal place |
| Recipe ingredients | Whole grams or quarter ounces |
| Shipping and postage | Round up to the next billing step |
| Lab and pharmacy work | Use the exact factor, then round at the end |
Plain answers
Pound to kilogram FAQ
How do you convert pound to kilogram?
Multiply the number of pounds by 0.45359237. That single factor converts any pound value to kilograms.
How many kilograms are in one pound?
One pound equals 0.45359237 kilograms.
What is 50 lb in kg?
50 pounds equals about 22.6796 kilograms.
Is the pound to kilogram conversion exact?
Yes. The factor is fixed by international definition, so pound to kilogram is an exact conversion rather than an estimate.
How can I estimate pound to kilogram in my head?
Halve the pounds and subtract about 10 percent, so 100 pounds is about 45 kg.