# How do I convert kg/m3 to lb/ft3?

Converts kilograms per cubic meter (kg/m³) to pounds per cubic foot (lb/ft³) and back, with the exact unit definitions.

- Page: https://www.acalculator.org/convert/kg-m3-to-lb-ft3
- JSON spec: https://www.acalculator.org/convert/kg-m3-to-lb-ft3.json
- Version: 768da0ff8f03

## Default answer

Example with the default inputs (Kilograms per cubic meter (kg/m³) 1): 1 kg/m³ = 0.062428 lb/ft³.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| value | Kilograms per cubic meter (kg/m³) | The amount in kilograms per cubic meter to convert. |
| result | Pounds per cubic foot (lb/ft³) | The same amount in pounds per cubic foot. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| value | Kilograms per cubic meter (kg/m³) | The amount in kilograms per cubic meter to convert. |
| result | Pounds per cubic foot (lb/ft³) | The amount in pounds per cubic foot. |

## Method

lb/ft³ = kg/m³ × 0.0624279605761 (the same as kg/m³ ÷ 16.018463374)

## Assumptions

- 1 kilogram per cubic meter = 0.0624279605761 pounds per cubic foot, from the exact definitions in NIST SP 811.
- Exact on the typed decimals: at most 6 decimal places (6 significant digits below 0.0001), rounded half up; an answer of 1 billion or more shows at most 15 significant digits.

## Worked examples

1. value = 1 gives result = 0.062428. Source: Exact unit definitions in NIST SP 811 (2008), Appendix B.8.
2. value = 1,000 gives result = 62.427961. Source: Exact unit definitions in NIST SP 811 (2008), Appendix B.8.
3. result = 1 gives value = 16.018463. Source: Exact unit definitions in NIST SP 811 (2008), Appendix B.8.

## FAQ

### How many pounds per cubic foot are in a kilogram per cubic meter?

1 kilogram per cubic meter is 0.062428 pounds per cubic foot, from the exact unit definitions (NIST SP 811).

### How do I convert kg/m3 to lb/ft3?

Multiply by 0.062428: lb/ft³ = kg/m³ × 0.0624279605761 (the same as kg/m³ ÷ 16.018463374). For example, 1 kg/m³ × 0.062428 = 0.062428 lb/ft³.

### How do I convert lb/ft3 back to kg/m3?

Multiply by 16.018463, or type the pounds per cubic foot into the second box and the converter works it out. 1 pound per cubic foot is 16.018463 kilograms per cubic meter.

### Where does the factor come from?

1 lb/ft³ is 0.45359237 kg ÷ 0.028316846592 m³ (1 lb = 0.45359237 kg and 1 ft = 0.3048 m exactly, NIST SP 811), 16.018463 kg/m³. So lb/ft³ = kg/m³ ÷ 16.018463…, or × 0.062428.

### What is the density of water in lb/ft³?

Pure water is 999.9749 kg/m³ at 4 °C, which is 62.426394 lb/ft³, and 998.2067 kg/m³ at 20 °C, 62.316009 lb/ft³ (Tanaka et al. 2001).

## Sources

- NIST SP 811 (2008), Guide for the Use of the International System of Units, Appendix B.8: Factors for Units Listed Alphabetically (bold factors are exact), retrieved 2026-10-19. https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8
- NIST SP 811 (2008), footnotes to Appendix B: 1 lb = 0.45359237 kg exactly (footnote 22); 1 lbf = 4.4482216152605 N exactly with standard gravity, 9.80665 m/s² (footnote 23), retrieved 2026-10-19. https://www.nist.gov/pml/special-publication-811/nist-guide-si-footnotes
- Tanaka, M. et al. (2001), Recommended table for the density of water between 0 °C and 40 °C based on recent experimental reports, Metrologia 38, 301–309: pure water 999.9749 kg/m³ at 4 °C and 998.2067 kg/m³ at 20 °C, retrieved 2026-10-19. https://doi.org/10.1088/0026-1394/38/4/3