Convert Pounds per Square Foot to Pounds per Square Inch
Convert Pounds per Square Foot (lbf/ft²) to Pounds per Square Inch (psi) instantly and accurately.
Conversion Formula
psi = lbf/ft² × 0.006944444444
About Pounds per Square Foot
One pound per square foot (psf) ≈ 47.88 Pa - the standard structural engineering load unit in US practice. Building codes specify design loads in psf: residential floors 40 psf; office buildings 50-80 psf; assembly areas 100+ psf; snow loads can exceed 100 psf. Wind pressure on building facades, soil bearing capacity for shallow foundations, and lateral earth pressure in retaining walls are all in psf. The related unit ksf (1,000 psf = 47.88 kPa) covers higher-capacity soils and deep foundations. 1 psf = 47.88 Pa.
About Pounds per Square Inch
One pound per square inch (psi) ≈ 6,894.76 Pa - the dominant pressure unit in US industry and consumer products. Car tyres: 32-36 psi; truck tyres 80-120 psi; bicycle road tyres 80-130 psi. Home water supply: 40-80 psi; residential maximum 80 psi per plumbing code. Compressed air tools: 90-150 psi. Steam autoclave sterilisation: 15-30 psi. The distinction between gauge (psig) and absolute (psia) pressure is critical: gauge pressure is relative to ambient; absolute = gauge + ~14.696 psi. 1 psi = 6,894.76 Pa.
Quick Reference Table
| Pounds per Square Foot (lbf/ft²) | Pounds per Square Inch (psi) |
|---|---|
| 1 lbf/ft² | 0.00694444 psi |
| 2 lbf/ft² | 0.0138889 psi |
| 5 lbf/ft² | 0.0347222 psi |
| 10 lbf/ft² | 0.0694444 psi |
| 25 lbf/ft² | 0.173611 psi |
| 50 lbf/ft² | 0.347222 psi |
| 100 lbf/ft² | 0.694444 psi |