Pounds per square foot (psf) is used for floor, roof and snow loads; psi for gauges and material strength. Because a square foot is 144 square inches, divide psf by 144 for psi.
How to use the PSF to PSI Converter
- Type the number of psf into the Psf field. Decimals such as 72 are fine.
- Read the answer in Psi. It updates as you type, with no button to press. The same amount is also shown in kPa, Pa, bar.
- To go from psi back to psf, type into the Psi field instead. Every field also has a unit menu with all 18 pressure units, for example Pa, kPa, MPa, GPa, hPa, bar, mbar, atm, ksi, mmHg, Torr.
Results update as you type, and everything is calculated in your browser.
How it works
Both units measure pressure, so they are always in the same ratio: one pound per square foot equals 0.0069444444 psi. The calculator multiplies the number of psf you type by 0.0069444444 to give psi, and when you type into the psi field it divides by the same factor to give psf. Because the ratio never changes, doubling the psf always doubles the psi, for example 288 psf is 2 psi.
How to convert psf to psi
- Write down the value in psf, for example 144 psf.
- Multiply by the conversion factor 0.0069444444 (because 1 pound per square foot = 0.0069444444 psi).
- 144 × 0.0069444444 = 1 psi.
- To go back from psi to psf, divide by 0.0069444444, or multiply by 144.
psf to psi conversion table
| Psf | Psi | Psi | Psf |
|---|---|---|---|
| 10 psf | 0.069444444 psi | 1 psi | 144 psf |
| 20 psf | 0.13888889 psi | 2 psi | 288 psf |
| 30 psf | 0.20833333 psi | 5 psi | 720 psf |
| 40 psf | 0.27777778 psi | 10 psi | 1,440 psf |
| 50 psf | 0.34722222 psi | 20 psi | 2,880 psf |
| 100 psf | 0.69444444 psi | 50 psi | 7,200 psf |
| 144 psf | 1 psi | 100 psi | 14,400 psf |
| 500 psf | 3.4722222 psi | 1,000 psi | 144,000 psf |
| 1,000 psf | 6.9444444 psi |
Pressure units explained
- Pound per square foot (psf)
- Pounds per square foot measures low pressures and loads, such as floor live loads, snow and wind loads in building codes. 144 psf equals 1 psi.
- Pound per square inch (psi)
- Pounds per square inch is the pressure of one pound-force on one square inch, about 6,895 Pa. U.S. tyre gauges, compressors and hydraulic equipment read psi.
Quick mental conversion
For a fast estimate, multiply psf by about 0.0069 to get psi; the error is about 0.6%. Use the calculator above when you need the exact figure.
Formula
1 pound per square foot = 0.0069444444 psi
1 pound per square inch = 144 psf
psi = psf × 0.0069444444
Worked example
Inputs: Psf: 144 psf.
Results: Psi = 1 psi; Kilopascals = 6.89475729 kPa; Pascals = 6,894.75729317 Pa; Bar = 0.06894757 bar.
Frequently asked questions
How many psi is 144 psf?
1 psi.
What is a typical floor live load?
About 40 psf for residential floors in U.S. codes.
How do I convert psf to psi?
Multiply the number of psf by 0.0069444444. For example, 144 psf × 0.0069444444 = 1 pound per square inch.
How do I convert psi back to psf?
Divide by 0.0069444444 (or multiply by 144), or simply type the value into the psi field above.
What is 10 psf in psi?
10 psf = 0.069444444 psi.
What is 100 psf in psi?
100 psf = 0.69444444 psi.
Is the psf to psi conversion exact?
Yes. The official definitions (NIST and the SI) fix 1 pound per square inch = 144 psf exactly, so the only difference you may see is rounding in the last displayed digit.