PSI to PSF Converter
A square foot holds 144 square inches. So to change psi to psf, multiply by 144.
Quick answer: multiply the pressure in psi by 144. For example, 1 psi is 144 psf, 10 psi is 1,440 psf and 100 psi is 14,400 psf.
The psi to psf formula
A psi is one pound-force on one square inch (Wikipedia: Pound per square inch).
A square foot is 12 by 12 inches, which is 144 square inches, so a psi is 144 psf.
Take 1 psi. Multiply by 144. The answer is 144 psf.
Take 10 psi. Multiply by 144. The answer is 1,440 psf.
Pounds per square inch to pounds per square foot
A psf is one pound-force on one square foot.
A psi is one pound-force on one square inch (Wikipedia: Pound per square inch).
One square foot holds 144 square inches, so the same pressure gives 144 times more pounds.
How to convert psi to psf step by step
- Write down the pressure in psi.
- Multiply it by 144.
- The answer is in psf.
- Check it against the chart above.
Example 1: 1 psi
- Start with 1 psi.
- 1 × 144 = 144.
- The pressure is 144 psf.
1 psi = 144 psf
Example 2: 10 psi
- Start with 10 psi.
- 10 × 144 = 1,440.
- The pressure is 1,440 psf.
10 psi = 1,440 psf
Example 3: 100 psi
- Start with 100 psi.
- 100 × 144 = 14,400.
- The pressure is 14,400 psf.
100 psi = 14,400 psf
The Structural load page gives a super imposed dead load of around 5 psf as common for buildings (Wikipedia: Structural load). That is only 0.0347 psi.
psi to psf conversion table
| psi | psf | Pa |
|---|---|---|
| 0.1 psi | 14.4 psf | 689.48 Pa |
| 0.5 psi | 72 psf | 3,447.38 Pa |
| 1 psi | 144 psf | 6,894.76 Pa |
| 5 psi | 720 psf | 34,473.79 Pa |
| 10 psi | 1,440 psf | 68,947.57 Pa |
| 14.696 psi | 2,116.22 psf | 101,325.35 Pa |
| 30 psi | 4,320 psf | 206,842.72 Pa |
| 100 psi | 14,400 psf | 689,475.73 Pa |
The highlighted row, 10 psi, is the default of the converter. The last column gives Pa.
A quick mental shortcut for psi to psf
Multiply by 144. Or multiply by 100, then add 44 percent.
So 10 psi is 1,440 psf.
What psi measures
A psi is one pound-force pressing on one square inch (Wikipedia: Pound per square inch).
US tyre gauges, tanks and hoses use it.
What psf measures
A psf is one pound-force on one square foot. It is 1/144 of a psi.
Building loads often use it.
Sea-level air
Air at sea level is about 14.696 psi, which is 2,116.2 psf.
That is the push of the air on each square foot.
Building loads
Building notes use psf for loads. A super imposed dead load of around 5 psf is common (Wikipedia: Structural load).
That is only 0.0347 psi.
A tyre
A tyre at 32 psi is 4,608 psf.
That is 220.6 kPa.
Gauge and absolute
Most gauges read pressure above the air around you. That is gauge pressure.
Absolute pressure adds about 1 atm, or 14.7 psi, at sea level (Wikipedia: Pressure).
Why the factor is 144
A square foot is 12 inches by 12 inches, which is 144 square inches.
So a psi is 144 psf.
Going the other way
To go back, divide the psf by 144.
So 1,440 psf is 10 psi.
Check your answer
Your psf should be 144 times the psi.
Divide it by 144 and you should get your first number.
More values at a glance
0.5 psi is 72 psf, 1 psi is 144 psf and 5 psi is 720 psf.
10 psi is 1,440 psf, 14.7 psi is 2,116.8 psf and 30 psi is 4,320 psf.
50 psi is 7,200 psf, and 100 psi is 14,400 psf.
The unit sizes
A square foot holds 144 square inches. So each psi is 144 psf.
If a result looks very large or very small, compare it with these sizes before you use it.
Checking in reverse
Convert 720 psf back to psi. You should get 5 psi.
Quick conversion answers
| Conversion | Result |
|---|---|
| 0.5 psi | 72 psf |
| 1 psi | 144 psf |
| 5 psi | 720 psf |
| 10 psi | 1,440 psf |
| 14.696 psi | 2,116.22 psf |
| 30 psi | 4,320 psf |
Round numbers for psi and psf
Use these round numbers to check your own answer. 5 psi is 720 psf, 50 psi is 7,200 psf and 500 psi is 72,000 psf.
Going the other way, 5,000 psf is 34.72 psi, 50,000 psf is 347.2 psi and 500,000 psf is 3,472 psi.
A round trip with psi
Say you start with 37 psi. It becomes 5,328 psf. Divide that by the factor and you land on 37 psi again.
Now start from 250,000 psf instead. It becomes 1,736 psi, and multiplying by the factor returns 250,000 psf.
Where this conversion is used
Tire and air tool gauges in the US read psi.
Building loads and wind pressure are often given in psf.
Builders compare load units.
Engineers read mixed sheets.
Common mistakes to avoid
- Mixing gauge and absolute pressure. Gauge pressure is read from the air around you.
- Using the wrong direction. Here 0.5 psi is 72 psf, so a correct answer comes out bigger than the number you start with.
- Mixing up similar units. Bar, atm and psi are close but not equal.
- Rounding too early. The answer for 1 psi is 144 psf. Cut it to 140 psf and you are off by about 2.8 percent, and the gap grows if you reuse it.
Related converters
A small test
A test at 0.5 psi is 72 psf.
In Pa that is 3,447.
A water supply
Mains water at 60 psi is 8,640 psf.
In kPa that is 413.7.
Frequently asked questions
How do I convert psi to psf?
Multiply the psi by 144.
How many psf is 1 psi?
144 psf.
How many psf is 14.696 psi?
About 2,116.2 psf.
How many psi is 1 psf?
About 0.006944 psi.
How many Pa is 1 psf?
About 47.88 Pa.
Why 144?
A square foot holds 144 square inches.
Sources
- Wikipedia: Pound per square inch (en.wikipedia.org)
- Wikipedia: Structural load (en.wikipedia.org)
- Wikipedia: Pascal (unit) (en.wikipedia.org)
