Pounds per Square Inch Calculator

Calculate pressure in pounds per square inch (psi) by entering force and area (or length × width). Enter any two values to solve for the third — PSI, force (lbf), or area (in²). Choose your preferred force unit, length unit, and pressure unit, and the calculator converts everything automatically. Results include the computed pressure alongside a visual breakdown of force vs. area.

Enter the total force applied

Length of the surface

Width of the surface

Only needed when calculating Force or Area

Results

Pressure (PSI)

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Pressure (Selected Unit)

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Area

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Force (lbf)

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Equivalent in kPa

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Equivalent in bar

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Force vs. Area Contribution

Frequently Asked Questions

What does PSI stand for?

PSI stands for pounds per square inch. It is a unit of pressure that describes the amount of force (in pounds) applied over an area of one square inch. It is commonly used in the US customary and imperial measurement systems.

How do I calculate pounds per square inch (PSI)?

PSI is calculated using the formula P = F / A, where P is pressure in psi, F is force in pound-force (lbf), and A is area in square inches (in²). If you know the length and width of a surface, the area equals length × width. Simply divide the force by the total area to get the pressure in PSI.

How much PSI should a car tire have?

Most passenger car tires require between 30 and 35 psi. The recommended tire pressure is usually printed on a sticker inside the driver's door or listed in the vehicle owner's manual. Always check tire pressure when the tires are cold for the most accurate reading.

How much PSI is 1 bar?

1 bar is equal to approximately 14.5038 psi. Conversely, 1 psi equals about 0.0689 bar. Bar is a metric unit of pressure commonly used in Europe and in scientific contexts.

How can I calculate the force if I know the pressure and area?

Rearranging the pressure formula gives F = P × A. Multiply the pressure (in psi) by the area (in square inches) to get the force in pound-force (lbf). This calculator supports solving for force directly — just select 'Calculate Force' from the dropdown.

What is the difference between psi and PSI (gauge vs. absolute)?

PSI can refer to either gauge pressure (psig) or absolute pressure (psia). Gauge pressure is measured relative to atmospheric pressure, while absolute pressure includes atmospheric pressure in the measurement. For most everyday applications like tire pressure, gauge pressure is used.

How do I convert PSI to kPa or other units?

To convert PSI to kilopascals (kPa), multiply by 6.89476. To convert to bar, multiply by 0.0689476. To convert to atmospheres (atm), multiply by 0.068046. This calculator performs these conversions automatically based on your selected output unit.

What are common uses for PSI measurements?

PSI is widely used to measure tire pressure, hydraulic system pressure, air compressor output, water pressure in pipes, and industrial equipment ratings. It is also used in scuba diving (tank pressure), medical devices, and engineering applications across many industries.

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