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psi - Pounds per Square Inch Pressure Unit

Pounds or pound force per square inch (psi, lb/in^2, pfsi or lbf/in^2) is a widely used British and American unit of measure for pressure. 1 psi equals 6,894.76 Pascals.

In the USA the PSI pressure unit is the pimary unit of measure for pressure and almost all pressure instruments are specified and display in pounds per square inch.

The psi is still used extensively in the UK but the bar pressure unit has mostly replaced it as the primary pressure unit.

Use the conversion factors below to convert from PSI to other pressure units or vice versa. To convert a reading in PSI to another unit multiply it by the relevant pressure conversion factor. To convert a reading in any pressure unit to PSI divide it by the relevant pressure conversion factor.

Alternatively convert from a psi pressure value into another unit using the psi conversion table or the pressure unit converter.

Find out how psi is derived from SI units and view the alternative descriptions for psi.



psi Pressure Conversion Factors
0.0689476 bar
1psi
68.9476 mbar
6894.76 N/m²
6894.76 Pa
68.9476 hPa
6.89476 kPa
0.00689476 MPa
0.0703070 kg/cm²
703.070 mmH2O 4°C (39.2°F)
70.3070 cmH2O 4°C (39.2°F)
0.703070 mH2O 4°C (39.2°F)
27.6799 inH2O 4°C (39.2°F)
2.30666 ftH2O 4°C (39.2°F)
51.7149 mmHg 0°C (32°F)
5.17149 cmHg 0°C (32°F)
2.03602 inHg 0°C (32°F)
51.7149Torr
51714.9 mTorr
0.0680460 atm
0.0703070 at
68947.6 dyn/cm²
16 oz/in²
51714.9 µHg 0°C (32°F)
0.000446429 tsi (uk, long)
0.000500000 tsi (usa, short)
0.0720000 tsf (usa, short)
144.000 psf
70.3070 g/cm²

Please note that the conversion factors above are accurate to 6 significant figures.

psi Derivation
The calculation below shows how the pressure unit pounds per Square inch (psi) is derived from SI Units.

Formula

Pressure = Force / Area
Force = Mass x Acceleration
Acceleration = Distance / (Second x Second)



SI Units

Mass: Kilogram (kg)
Length: Metre (m)
Time: Second (s)
Force: Newton (N)
Pressure: Pascal (Pa)



Input Values

1 Pound = 0.45359237 kg
1 Inch = 0.0254 m
1 Square Inch = 0.0254 m x 0.0254 m = 0.00064516 m²
Acceleration = Standard Gravity = 9.80665 m/s²



Calculation

1 Pound Force = 0.45359237 kg x 9.80665 m/s² = 4.448221615 N
1 psi Pressure = 4.448221615 N / 0.00064516 m² = 6894.757293 Pa

psi Alternate Descriptions

These are the different versions used for identifying psi that you may find elsewhere.

Pounds Per Square Inch
Pound Per Square Inch
Pounds Force Per Square Inch
Pound Force Per Square Inch
psi
pfsi
lb/in²
lbf/in²
lb/sq in
lbf/sq in
lb/in^2
lbf/in^2 lbs/in²
lbsf/in²
lbs/sq in
lbsf/sq in
lbs/in^2
lbsf/in^2

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Site Last Updated:  04/02/12

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