Converters Pounds to kilograms
Convert pounds to kilograms with the exact factor, plus body weight, luggage allowance and gym plate references.
1 lb = 0.45359237 kg
kilograms = pounds × 0.45359237
pounds to kilograms
| lb | kg |
|---|---|
| 1 | 0.453592 |
| 2 | 0.907185 |
| 3 | 1.360777 |
| 4 | 1.814369 |
| 5 | 2.267962 |
| 10 | 4.535924 |
| 15 | 6.803886 |
| 20 | 9.071847 |
| 25 | 11.339809 |
| 50 | 22.679619 |
| 75 | 34.019428 |
| 100 | 45.359237 |
| 500 | 226.796185 |
| 1,000 | 453.59237 |
One pound is exactly 0.45359237 kilograms.
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Reembun. (2026, July 28). Pounds to kilograms. https://reembun.com/convert/weight/lbs-to-kg
How to use it
Type the pounds
Kilograms appear immediately, to as many decimals as the value needs.
Go the other way
Swap units turns it into a kilograms to pounds converter.
Copy it or read the table
The table lists the weights people convert most often, already worked out to the same precision.
The formula
kilograms = pounds × 0.45359237
pounds = kilograms × 2.2046226218The factor is exact by definition. Since 2019 the kilogram itself has been defined by fixing the Planck constant, replacing the platinum-iridium cylinder that had served as the standard since 1889 and had measurably lost mass over that time.
Quick reference
| lb | kg | lb | kg |
|---|---|---|---|
| 10 | 4.54 | 150 | 68.04 |
| 20 | 9.07 | 160 | 72.57 |
| 50 | 22.68 | 175 | 79.38 |
| 100 | 45.36 | 200 | 90.72 |
| 120 | 54.43 | 250 | 113.40 |
| 140 | 63.50 | 300 | 136.08 |
Baggage allowances
Airline limits are set in whichever unit the carrier prefers, and rounded rather than converted.
| Allowance | Metric | Imperial |
|---|---|---|
| Typical checked bag | 23 kg | 50 lb |
| Heavier allowance | 32 kg | 70 lb |
| Cabin bag | 7 kg | 15 lb |
| Cabin bag, some carriers | 10 kg | 22 lb |
Note that 23 kg is 50.7 lb and 50 lb is 22.68 kg. The two figures are the same allowance described in different units, not two different limits.
Barbell plates
| Metric plate | Imperial equivalent | Actual |
|---|---|---|
| 25 kg | 55 lb | 55.1 lb |
| 20 kg | 45 lb | 44.1 lb |
| 15 kg | 35 lb | 33.1 lb |
| 10 kg | 25 lb | 22.0 lb |
| 5 kg | 10 lb | 11.0 lb |
The bar itself is 20 kg or 45 lb, which are not the same weight, since 45 lb is 20.4 kg. Loading a “225 lb” bar with metric plates gives 102.1 kg rather than 102.06, close enough for training and not close enough for competition.
Mental arithmetic
lb → kg: halve, then subtract 10%. 180 lb → 90 − 9 = 81 kg. (True: 81.65)
kg → lb: double, then add 10%. 75 kg → 150 + 15 = 165 lb. (True: 165.3)
Both approximations run about 0.2% low, well inside the tolerance of any bathroom scale.
Where each unit is used
The kilogram is the SI base unit and standard almost everywhere. Pounds persist in the United States for body weight, food packaging and freight. The UK is a hybrid: shops sell in kilograms by law, while people describe their own weight in stone and pounds.
For anything medical, use kilograms without exception.
Common questions
What is the exact factor?
One pound is exactly 0.45359237 kilograms, defined by the International Yard and Pound Agreement of 1959. One kilogram is 2.2046226218 pounds. The everyday shorthand of 2.2 is accurate to within 0.2%.
How do I convert in my head?
Halve it, then subtract 10%. For 180 lb: 90 minus 9 gives 81 kg. The true answer is 81.65, so the shortcut runs slightly low, fine for a rough figure but not for a dose.
Why do gyms in metric countries use pound plates?
Many do not, but competition plates follow IWF standards in kilograms while a lot of commercial gym equipment is manufactured to US specifications in pounds. Mixed racks are common enough that checking the stamp before loading a bar is worth the second it takes.
Which unit should I use for medication?
Kilograms, always. Drug dosing is calculated per kilogram of body mass worldwide, and unit confusion in that context is a documented cause of serious harm. Never convert a dose yourself from a weight in pounds without checking.
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