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.
- To convert the other way, type into Psi and the psf are recalculated.
- Press Copy results to copy both values with the page title, or Copy link to share this exact conversion.
This page converts only psf ⇄ psi. Need a different unit? Use the general pressure converter, where you can choose any “from” and “to” unit.
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. Results are calculated at full precision and rounded only for display (up to eight decimal places, with very large or small values shown in scientific notation).
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 |
What is a pound per square foot?
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.
What is a pound per square inch?
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.
Common mistakes to avoid
Mixing gauge pressure (psig, barg) with absolute pressure (psia, bara), treating bar and atm as identical, and confusing kgf/cm² with bar.
Formula
1 psf = 0.0069444444 psi1 psi = 144 psfpsi = psf × 0.0069444444Worked example
Inputs — Psf: 144 psf.
Results — Psi = 1 psi.
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 psi.
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 this conversion exact?
Yes. The factor comes from the official definitions of both units (NIST and the SI), so the only difference you may see is rounding in the last displayed digit.
Can I convert to other units on this page?
This page converts only between psf and psi. To pick any pressure unit, use the general pressure converter linked under Related calculators.
What formula does the PSF to PSI Converter use?
1 psf = 0.0069444444 psi.