Pounds to Kilograms Calculator
Enter a weight in pounds (lb), then click convert to get the result in kilograms (kg).
How to convert pounds to kilograms
The pound (lb) is a common unit of weight in the United States and a few other countries, while the kilogram (kg) is the standard metric unit used worldwide. If you are tracking fitness progress, reading medical records, traveling, or shipping packages internationally, converting pounds to kilograms is often necessary.
This calculator gives you a fast and accurate lbs to kg conversion. Enter any number, including decimals, and get the exact metric value instantly.
The conversion formula
Exact formula
kilograms = pounds × 0.45359237
That constant is the official definition used for precise conversion. For everyday use, some people round it to 0.454, but using the full value gives better accuracy.
Example calculation
- 150 lb × 0.45359237 = 68.0388555 kg
- Rounded result: 68.04 kg
Quick conversion chart (lb to kg)
| Pounds (lb) | Kilograms (kg) |
|---|---|
| 1 | 0.4536 |
| 5 | 2.2680 |
| 10 | 4.5359 |
| 25 | 11.3398 |
| 50 | 22.6796 |
| 100 | 45.3592 |
| 150 | 68.0389 |
| 200 | 90.7185 |
| 250 | 113.3981 |
When this pounds to kg converter is useful
1) Health and fitness
Many workout plans and nutrition programs are written in metric units. If your scale uses pounds, this tool helps you compare your progress with kg-based targets.
2) Medical and scientific contexts
Medical charts, dosage guidelines, and scientific documents usually use kilograms. Accurate conversion avoids mistakes and improves communication.
3) Travel and shipping
Airlines and shipping providers typically display luggage and package limits in kilograms. Converting from pounds helps you avoid overweight fees and planning issues.
Tips for accurate conversions
- Use decimal values when needed (for example, 132.5 lb).
- Round only at the final step if precision matters.
- For legal, medical, or engineering use, keep at least 3–4 decimal places.
- Double-check units before entering data: lb and kg are not interchangeable.
Frequently asked questions
Is 1 pound exactly 0.45 kg?
Not exactly. 1 pound equals 0.45359237 kg. Using 0.45 is a rough estimate only.
How many kilograms is 180 pounds?
180 lb is approximately 81.65 kg.
Can I convert fractional pounds?
Yes. This calculator supports decimal and fractional-style input values entered as decimals, such as 2.5 lb or 175.75 lb.
Final thoughts
If you need a quick, reliable pounds to kilograms conversion, this calculator is designed to keep things simple. Enter pounds, click once, and get a precise result in kg—perfect for everyday use, fitness tracking, and professional tasks where accurate weight conversion matters.