# Pounds to kilograms converter

> Convert pounds to kilograms (lbs to kg) with the exact factor, a conversion chart and worked steps.

Interactive version: https://www.calcopenly.com/conversion/lbs-to-kg
Subject: Unit converters

Pounds are often used on parcel labels and equipment specifications. This is avoirdupois mass, rather than a force rating. If the source gives pounds plus ounces, combine them correctly before conversion. A carrier's billed weight can also depend on package dimensions.

One pound is exactly 0.45359237 kilograms, so 150 lb is 68.038856 kg. To convert lbs to kg, multiply by 0.45359237; to convert back, multiply by 2.2046226218.

The international avoirdupois pound is defined as exactly 0.45359237 kg (1959 agreement). Because both units are defined exactly, the factor above is exact and the results here carry no conversion error.

## Inputs

- **Pounds (lb)**

## Results

- Kilograms (kg) — main result
- Conversion
- 1 kg in pounds (lb)

## Formula

$$
\text{kilograms} = \text{pounds} \times 0.45359237
$$

## Worked examples

### 150 lb to kg

- Pounds (lb): 150 lb
- **Kilograms: 68.0388555 kg**
- Checked against: Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions)

### 20 lb to kg

- Pounds (lb): 20 lb
- **Kilograms: 9.0718474 kg**
- Checked against: Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions)

### 200 lb to kg

- Pounds (lb): 200 lb
- **Kilograms: 90.718474 kg**
- Checked against: Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions)

## Questions

### When would I convert lbs to kg?

Pounds are often used on parcel labels and equipment specifications. This is avoirdupois mass, rather than a force rating. If the source gives pounds plus ounces, combine them correctly before conversion. A carrier's billed weight can also depend on package dimensions.

### How many kilograms are in a pound?

One pound is exactly 0.45359237 kilograms. The international avoirdupois pound is defined as exactly 0.45359237 kg (1959 agreement).

### How do you convert lbs to kg?

Multiply the number of pounds by 0.45359237. For example, 150 lb × 0.45359237 = 68.038856 kg. To go the other way, divide by 0.45359237.

### How can I estimate lbs to kg without a calculator?

Multiply by 0.45. That is 0.8% low of the exact factor 0.45359237, so 150 lb comes out as 67.5 kg instead of 68.0389.

### How accurate is the pounds to kilograms converter?

Accuracy depends on your inputs and the method's assumptions. Decimal arithmetic uses 50 significant digits, but estimates, numerical methods and source data can be less precise; the displayed rounding does not remove those limits. It is checked against 3 worked examples whose answers come from independent sources; for example, “150 lb to kg” is checked against Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions).

### Where does the method come from?

NIST SP 811 (2008), Guide for the Use of the International System of Units, Appendix B; NIST Handbook 44, Appendix C: General tables of units of measurement; BIPM, The International System of Units (SI Brochure), 9th edition.

## Sources

- [NIST SP 811 (2008), Guide for the Use of the International System of Units, Appendix B](https://www.nist.gov/pml/special-publication-811)
- [NIST Handbook 44, Appendix C: General tables of units of measurement](https://www.nist.gov/pml/weights-and-measures/publications/nist-handbooks/handbook-44)
- [BIPM, The International System of Units (SI Brochure), 9th edition](https://www.bipm.org/en/publications/si-brochure)