Pressure conversion factor from psf to psi

Analyzing psf and psi Units#

In this article, we'll explore pressure units and calculate the conversion factor from psf to psi.

• psf stands for pound-force per square foot, and is a common US unit for pressure. It's often informally referred to as pounds per square foot, although not entirely accurate.
• psi stands for pound-force per square inch, and is a common US unit for pressure. It's often informally referred to as pounds per square inch, although not entirely accurate.

As we delve into converting pressure units, we'll see that pressure relies on three fundamental quantities: mass, length, and time:

Pressure = force / area
         = mass · acceleration / area
         = mass · speed / time / area
         = mass · length / time² / length²
         = mass / time² / length

Given that both units are US units, and the only difference is the spread area, we'll only need the equivalence between ft and in to find the conversion factor.

How to Convert Pressure psf to psi#

The equivalence between inches and feet:

ft = 12 in
in = 1/12 ft

Starting with the definition of pressure (force / area), we can convert in units to ft:

psi = lbf / in²
    = lbf / (in)²
    = lbf / (1/12 ft)²
    = lbf / (1/144 ft²)
    = 144 lbf / ft²
    = 144 psf

Now, we can divide both sides of the equation by 144 psf:

psi / (144 psf) = 1

This manipulation provides us with the left side of the equation as a convenient conversion factor.

factor = psi / (144 psf)
       = 1 / 144 psi / psf
       ≈ 0.006944444444444444 psi / psf

Applying this conversion factor to a pressure in psf, psf units cancel out, and we're left with the unit we're aiming for: psi.

Convert 3000 psf to psi#

Here's an example of how to convert a pressure of 3000 psf into psi:

3000 psf · factor
= 3000 psf · 0.006944444444444444 psi / psf
= 3000 · 0.006944444444444444 psi
= 20.833333333333332 psi

psf to psi Conversion Factor#

Here're the resulting key takeaways.

1 psi = 144 psf

Converting a psf unit into psi is as simple as multiplying it by a conversion factor:

psi = psf · factor

where factor is exactly:

factor = 1 / 144

or approximately:

factor ≈ 0.006944444444444444

Explore More#

Here are some additional resources to deepen into this topic:

• Convert Pressure Units with this Converter.
• Check out other worked examples of how pressure conversion factors can be derived: MPa to psi, psi to MPa, psi to psf, or psi to ksi.
• Check out other worked examples of how pressure conversion factors can be derived: psi to psf, MPa to psi, psf to psi, or psi to ksi.
• Check out other worked examples of how force conversion factors can be derived: lbf to N, kN to lbf, and lbf to kN.