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Rectangular Contact Pressure in PSI & Pascals

Calculate average pressure from normal force and a rectangular contact area, with optional pressure-unit conversion.

  • 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 normal force of 100 lbf over a rectangle 2 inches by 5 inches gives an average pressure of 10 psi.

Average pressure = normal force ÷ (length × width)

Worked example

Enter these known values and leave the other values blank.

Normal contact force
100 lbf
Contact length
2 in
Contact width
5 in
Additional pressure display
Show pressure in other units
Average pressure (psi)
10 psi
Pressure in other units
68948 Pa

Assumptions and limitations

  • Length and width are positive. Force and pressure are nonnegative magnitudes.
  • Pressure is the average normal force over the rectangular area. Actual contact pressure can be nonuniform.
  • This area calculation does not assess structural capacity, material strength or equipment pressure ratings. Pounds-force are force, not pounds of mass.

Common questions

Is one pound of mass the same as one pound-force?

No. They measure different quantities. Use a force value or convert weight under an explicitly chosen gravitational acceleration.

Can I recover force from pressure?

Yes. Enter pressure, contact length and contact width. Their product gives normal force.

References

Bookify allows zero contact force and pressure while retaining positive contact dimensions. Mercury pressure columns use conventional density and standard gravity, with the exact international inch. The pound-force uses the exact international pound and standard gravity instead of the rounded captured factor. The poundal uses exactly one international pound-foot per second squared. 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.

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