Convert Pounds-force per Cubic Foot to kN/m³
1 pound-force per cubic foot (lbf/ft³) = 0.1570874638 kilonewtons per cubic metre (kN/m³). 1 kN/m³ = 6.365880354 lbf/ft³. Example: 120 lbf/ft³ = 120 × 0.1570874638 = 18.85049566 kN/m³.
Also searched as pcf to kN/m3, lb/ft3 to kN/m3, unit weight pcf to kn/m³ and pounds per cubic foot to kilonewtons per cubic meter.
1 lbf/ft³ = 0.1570874638 kN/m³
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk pcf to kilonewton per cubic metre converter to paste a column from Excel.
How to Convert Pound-force per Cubic Foot to Kilonewton per Cubic Metre
- 1 lbf/ft³ = 0.1570874638 kN/m³
- 1 kN/m³ = 6.365880354 lbf/ft³
- Example: convert 120 lbf/ft³ to kN/m³: 120 lbf/ft³ = 120 × 0.1570874638 kN/m³ = 18.85049566 kN/m³
Formula
kN/m³ = lbf/ft³ × 0.1570874638462
or kN/m³ = lbf/ft³ ÷ 6.365880354264
Derivation from SI units:
- 1 lbf/ft³ = 4.4482216152605 N ÷ 0.028316846592 m³ ≈ 157.087 N/m³.
- 1 kN/m³ = 1000 N/m³.
- 1 lbf/ft³ = 157.0874638462 N/m³ ÷ 1000 N/m³ per kN/m³ = 0.1570874638462 kN/m³
Both units are defined exactly, so the factor is exact. Pound-force per Cubic Foot definition: pound-force per cubic foot; Kilonewton per Cubic Metre definition: kilonewton per cubic metre.
Worked examples
- A compacted soil of 120 lbf/ft³ is 18.85049566 kN/m³.
120 lbf/ft³ × 0.1570874638 = 18.85049566 kN/m³ - Normal-weight concrete at 150 lbf/ft³ is 23.56311958 kN/m³.
150 lbf/ft³ × 0.1570874638 = 23.56311958 kN/m³
Pound-force per Cubic Foot to Kilonewton per Cubic Metre conversion table
| Pounds-force per Cubic Foot (lbf/ft³) | Kilonewtons per Cubic Metre (kN/m³) |
|---|---|
| 62.4 lbf/ft³ | 9.802257744 kN/m³ |
| 90 lbf/ft³ | 14.13787175 kN/m³ |
| 100 lbf/ft³ | 15.70874638 kN/m³ |
| 110 lbf/ft³ | 17.27962102 kN/m³ |
| 115 lbf/ft³ | 18.06505834 kN/m³ |
| 120 lbf/ft³ | 18.85049566 kN/m³ |
| 125 lbf/ft³ | 19.63593298 kN/m³ |
| 145 lbf/ft³ | 22.77768226 kN/m³ |
| 150 lbf/ft³ | 23.56311958 kN/m³ |
| 490 lbf/ft³ | 76.97285728 kN/m³ |
Where it's used
Soil and concrete unit weights in pcf from US geotechnical reports and ACI are converted to kN/m³ for SI design. Multiply by 0.157087.
Pound-force per Cubic Foot to other unit weight units
| Conversion | 1 lbf/ft³ equals |
|---|---|
| pcf to kilonewton per cubic metre | 0.1570874638 kN/m³ |
| pcf to newton per cubic metre | 157.0874638 N/m³ |
| pcf to tonne-force per cubic metre | 0.01601846337 tf/m³ |
| pcf to kilogram-force per cubic metre | 16.01846337 kgf/m³ |
| pcf to gram-force per cubic centimetre | 0.01601846337 gf/cm³ |
| pcf to pound-force per cubic inch | 0.0005787037037 lbf/in³ |
Frequently asked questions
How many kN/m³ is 1 pcf?
1 pcf = 0.1570874638 kN/m³; water at 62.4 pcf is 9.802257744 kN/m³.
Is pcf mass or weight?
In soil mechanics pcf is a unit weight (lbf/ft³). Numerically, a density of 1 lb/ft³ under standard gravity weighs 1 lbf/ft³.
How many kilonewtons per cubic metre are in 1 pound-force per cubic foot?
1 lbf/ft³ = 0.1570874638 kN/m³.
How do I convert pounds-force per cubic foot to kilonewtons per cubic metre?
Multiply the value in lbf/ft³ by 0.1570874638, or divide it by 6.365880354. For example, 120 lbf/ft³ × 0.1570874638 = 18.85049566 kN/m³.
Is the lbf/ft³ to kN/m³ conversion exact?
Yes. Both units are defined exactly, so the ratio is exact; its decimal form does not terminate and is shown here to 10 significant figures (more with the precision selector).
Sources
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "pound-force per cubic foot".
- The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures , Table 4 (derived units) and Table 8 (non-SI units accepted for use with the SI).
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Convert Pounds-force per Cubic Foot to kN/m³. Retrieved October 29, 2026, from https://scientificconverters.com/specific-weight/pounds-force-per-cubic-foot-to-kilonewtons-per-cubic-meter/
IEEE
Scientific Converters, "Convert Pounds-force per Cubic Foot to kN/m³," scientificconverters.com. Accessed: Oct. 29, 2026. [Online]. Available: https://scientificconverters.com/specific-weight/pounds-force-per-cubic-foot-to-kilonewtons-per-cubic-meter/