One pound per square foot is exactly 0.006944444444 pounds per square inch, so converting pounds per square foot to pounds per square inch is a single multiplication. Enter any figure and the result appears as you type — the arithmetic runs in your browser, so nothing is sent anywhere.
The unit US building codes give floor, roof and wind loads in. The dominant US pressure unit for tyres, plumbing and compressors.
Gauge versus absolute. A tyre gauge reading 32 psi means 32 psi above atmospheric, which is about 46.7 psi absolute. Converting the number is straightforward; remembering which zero it was measured from is where the mistakes happen. N/mm² and MPa are the same size, so a drawing quoting either is quoting the same stress. Two tables follow: rounded steps for quick lookup, and a set of real reference quantities converted into pounds per square inch, which is usually more useful than the bare number.
The formula
pounds per square foot- The amount you are converting, in pounds per square foot
0.00694444444444- The exact number of pounds per square inch in one pound per square foot
pounds per square inch- The converted result
How it works, step by step
- Enter the value in pounds per square foot.
- It is multiplied by 0.00694444444444, the exact factor between the two units.
- The answer is shown in pounds per square inch, with the reverse conversion beneath it.
- Check the reference table if you want a figure of comparable size.
Worked examples
Blood pressure, systolic: 334 psf in pounds per square inch
Take blood pressure, systolic, roughly 334 psf. The conversion is a single multiplication — 334 × 0.00694444 — giving 2.31944 psi. Because the relationship is proportional, doubling the input doubles the answer to 4.63889 psi.
A domestic water main: 8350 psf in pounds per square inch
At 8350 psf (a domestic water main), the same quantity in pounds per square inch is 8350 × 0.00694444 = 57.9861 psi. One pound per square foot is 0.00694444 pounds per square inch, so the numbers shrink as expected.
How to read your score
Frequently asked questions
How many pounds per square inch are in one pound per square foot?
Exactly 0.00694444444444. Every figure on this page is that one number multiplied by your input, so the only rounding is at the display step.
What is the formula to convert pounds per square foot to pounds per square inch?
pounds per square inch = pounds per square foot × 0.00694444444444. Reversed, pounds per square foot = pounds per square inch ÷ 0.00694444444444, which is the same as multiplying by 144.
Which is the bigger unit, the pound per square foot or the pound per square inch?
The pound per square inch. One pound per square foot is only 0.00694444 of a pound per square inch, so it takes 144 pounds per square foot to make one pound per square inch.
What does this quantity actually measure?
Both units measure pressure. That is why a single factor is enough: there is no temperature offset and no material property involved, unlike conversions that cross between different quantities.
What is a pound per square foot?
The unit US building codes give floor, roof and wind loads in.
What is a pound per square inch?
The dominant US pressure unit for tyres, plumbing and compressors.
Why does my answer differ from another converter?
Almost always because the other tool rounded the factor before multiplying. This page keeps full double precision through the calculation and rounds only for display, and it prints the factor it used so you can see where any difference came from.
Is there a quick way to do psf to psi in my head?
Plenty of people do this in their head: divide by 140 instead of using the exact factor 0.006944444444. At 100 that shortcut gives 0.71428571 pounds per square inch, off by 0.01984 pounds per square inch or about 2.86%. Fine for a rough estimate, not fine for anything you are cutting to size or dosing.
Pounds Per Square Foot to pounds per square inch reference tables
| Pounds Per Square Foot | Pounds Per Square Inch |
|---|---|
| 0.5 psf | 0.00347222 psi |
| 1 psf | 0.00694444 psi |
| 2 psf | 0.0138889 psi |
| 3 psf | 0.0208333 psi |
| 5 psf | 0.0347222 psi |
| 10 psf | 0.0694444 psi |
| 20 psf | 0.138889 psi |
| 25 psf | 0.173611 psi |
| 50 psf | 0.347222 psi |
| 75 psf | 0.520833 psi |
| 100 psf | 0.694444 psi |
| 250 psf | 1.73611 psi |
| 500 psf | 3.47222 psi |
| 1000 psf | 6.94444 psi |
| 5000 psf | 34.7222 psi |
Exact factor: 1 pound per square foot = 0.00694444444444 pounds per square inch.
| Quantity | psf | psi |
|---|---|---|
| Sea-level air | 2116 psf | 14.7 psi |
| A car tyre | 4608 psf | 32 psi |
| Blood pressure, systolic | 334.1 psf | 2.32 psi |
| A bicycle tyre | 1.296e+04 psf | 90 psi |
| A domestic water main | 8354 psf | 58.02 psi |
| A steam boiler | 2.089e+04 psf | 145 psi |
Published reference values, converted with the same factor this page uses.