Pound per Square Inch (psi)
An imperial unit of pressure commonly used in the US
The Pound per Square Inch (psi) is a unit of pressure with a history connected to the study of fluids, gases, and atmospheric phenomena. Evangelista Torricelli's invention of the barometer in 1643 was a landmark in pressure measurement, and subsequent work by Blaise Pascal established the mathematical foundations. The pascal — the SI unit — was named in Pascal's honor when the SI system was formalized. The Pound per Square Inch reflects either the SI tradition or the practical conventions of specific industries that standardized their measurements independently.
Accurate pressure measurement is critical in engineering, science, commerce, and everyday life. Using the correct unit and applying conversions precisely prevents errors that can be costly or dangerous in professional applications.
Conversion Table
| Unit | Symbol | 1 psi = |
|---|---|---|
| Pascal | Pa | 6894.76 Pa |
| Kilopascal | kPa | 6.89476 kPa |
| Bar | bar | 0.0689476 bar |
| Atmosphere | atm | 0.068046 atm |
| Millimeters of Mercury | mmHg | 51.7151 mmHg |
| Megapascal | MPa | 0.00689476 MPa |
| Gigapascal | GPa | 0.00000689476 GPa |
| Kilopound per Square Inch | ksi | 0.001 ksi |
| Torr | torr | 51.7151 torr |
| Inch of Mercury | inHg | 2.03602 inHg |
| Kilogram-force per Square Centimeter | kgf/cm² | 0.070307 kgf/cm² |
Conversions Involving Pound per Square Inch
Pascal → Pound per Square Inch
Pa → psi
Kilopascal → Pound per Square Inch
kPa → psi
Bar → Pound per Square Inch
bar → psi
Atmosphere → Pound per Square Inch
atm → psi
Pound per Square Inch → Pascal
psi → Pa
Pound per Square Inch → Kilopascal
psi → kPa
Pound per Square Inch → Bar
psi → bar
Pound per Square Inch → Atmosphere
psi → atm
Pound per Square Inch → Millimeters of Mercury
psi → mmHg
Pound per Square Inch → Megapascal
psi → MPa
Pound per Square Inch → Gigapascal
psi → GPa
Pound per Square Inch → Kilopound per Square Inch
psi → ksi
Pound per Square Inch → Torr
psi → torr
Pound per Square Inch → Inch of Mercury
psi → inHg
Pound per Square Inch → Kilogram-force per Square Centimeter
psi → kgf/cm²
Millimeters of Mercury → Pound per Square Inch
mmHg → psi
Megapascal → Pound per Square Inch
MPa → psi
Gigapascal → Pound per Square Inch
GPa → psi
Kilopound per Square Inch → Pound per Square Inch
ksi → psi
Torr → Pound per Square Inch
torr → psi
Inch of Mercury → Pound per Square Inch
inHg → psi
Kilogram-force per Square Centimeter → Pound per Square Inch
kgf/cm² → psi
Common Uses of the Pound per Square Inch
- •Automotive — inflating tires to manufacturer-specified pressures
- •Weather reporting — tracking barometric pressure for forecasting
- •Hydraulic systems — designing and operating fluid power equipment
- •Scuba diving — calculating safe dive depths based on partial pressures
- •Medical — measuring blood pressure and calibrating medical equipment
Did You Know?
The deepest point in the ocean — the Challenger Deep in the Mariana Trench — has a water pressure of approximately 110 MPa, or about 1,086 times standard atmospheric pressure. The Pound per Square Inch is one of several units used to express pressures across this extraordinary range.