Free · Pressure converters

Pounds per Square Foot to PSI

Convert pressure between pound-force per square foot and pound-force per square inch, with additional pressure units.

  • Formula & worked example
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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

Private by default

Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.

Formula and method

A pressure of 144 pound-force per square foot equals 1 psi because one square foot contains 144 square inches.

psi = pound-force per square foot / 144

Worked example

Enter these known values and leave the other values blank.

Pressure, initially pound-force per square foot
144 lbf/ft²
Equivalent pressure, initially psi
1 psi

Assumptions and limitations

  • The input is force per area, not mass in pounds by itself. Converting a total force to pressure also requires the loaded area.
  • Ordinary pressure units preserve the same pressure reference. Signed pressure differences can be converted when both measurements use that reference.
  • The optional psig unit is a special gauge-to-absolute conversion using the fixed reference 101,325 Pa. Do not use that offset for a pure pressure difference or assume it measures local atmospheric pressure.

Common questions

Why divide by 144?

One foot is twelve inches, so one square foot covers twelve times twelve square inches. The same total force is spread over 144 square inches.

Can I convert a load in pounds directly to psi?

Only after specifying its effective area and whether the pounds represent force. This calculator’s starting unit is already pressure.

References

Mercury pressure columns use conventional density and standard gravity, with the exact international inch. Gauge PSI uses the exact PSI factor and the captured fixed ambient offset of 101325 Pa; it does not measure local atmospheric pressure. Pounds-force per square inch use the exact international pound and inch with standard gravity, replacing the rounded captured factor. One technical atmosphere is exactly one kilogram-force per square centimeter under standard gravity. Pounds-force per square foot use the exact international pound and foot with standard gravity. The tonnes-force pressure option uses metric tonnes and standard gravity, with one tonne-force per square meter equal to 9806.65 pascals. Ksi uses exactly one thousand of the same reviewed pounds-force per square inch.

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