What is pound per square inch?
Pound per square inch (psi) is an imperial pressure unit widely used in the United States for tire inflation, hydraulic system pressures, gas cylinder ratings, and plumbing specifications.
Real-world uses
PSI is the standard pressure unit in the United States for tyre inflation (typically 30–35 psi for cars), compressed air tools, hydraulic systems, and water pressure. HVAC systems, fire extinguisher ratings, and pressure cooker specifications use psi in North America.
History
Pounds per square inch emerged naturally from the Imperial/US customary system, combining the pound-force with the square inch. It became the dominant pressure unit in American industry and remains deeply embedded in US engineering standards and building codes.
Common mistakes
Not distinguishing between psi (absolute, psia) and psig (gauge, relative to atmosphere). A tyre reading of 32 psig actually means about 46.7 psia. Also, confusing psi with kPa when using equipment from metric countries.
What is pascal?
The pascal is the SI base unit of pressure, equal to one newton per square metre. It is used in meteorology, fluid dynamics, materials science, and all scientific pressure measurements.
Real-world uses
The pascal is the SI unit of pressure used in engineering stress analysis, materials science, and acoustics (sound pressure levels). Concrete and steel specifications list compressive strength in megapascals (MPa). Atmospheric pressure is about 101,325 Pa.
History
Named after Blaise Pascal, the French mathematician and physicist who conducted pioneering experiments on fluid pressure and vacuum in the 1640s. The pascal was adopted as the SI unit of pressure in 1971 at the 14th General Conference on Weights and Measures.
Common mistakes
Using pascals directly for everyday pressure is impractical since one pascal is a very small pressure (about the weight of a dollar bill spread over a desk). Most practical applications use kPa, hPa, or MPa instead.
When is this conversion used?
Converting between pound per square inch and pascal is common when working across metric and imperial systems, such as international trade, travel between countries with different measurement standards, or following instructions from a different region. Tyre pressure gauges, HVAC systems, and industrial equipment may use different pressure units depending on the manufacturer and region. Converting between psi, bar, and kPa is common in automotive and engineering work.
Worked examples
1 pound per square inch = 6,894.75729317 pascal
1 pascal = 1 pascal
How to convert pound per square inch to pascal
To convert pound per square inch to pascal, multiply the value by 6,894.75729317.
To convert pascal back to pound per square inch, multiply by 0.00014504.
Measurement standards
The pascal (Pa) is the SI derived unit of pressure, defined as one newton per square metre. The World Meteorological Organization mandates the hectopascal (hPa) for atmospheric pressure reporting in aviation and weather services.
Did you know?
The pressure at the bottom of the Mariana Trench, nearly 11 km deep, exceeds 1,086 bar — over a thousand times atmospheric pressure. At this depth, water is compressed by about 5%, making it measurably denser than at the surface.
Quick reference: pound per square inch to pascal
| pound per square inch | pascal |
|---|---|
| 0.1 | 689.47572932 |
| 0.5 | 3,447.37864658 |
| 1 | 6,894.75729317 |
| 2 | 13,789.51458634 |
| 5 | 34,473.78646584 |
| 10 | 68,947.57293168 |
| 25 | 172,368.9323292 |
| 50 | 344,737.8646584 |
| 100 | 689,475.7293168 |
| 250 | 1,723,689.323292 |
| 500 | 3,447,378.646584 |
| 1,000 | 6,894,757.293168 |
Common values
| pound per square inch | pascal | |
|---|---|---|
| Car tyre | 31.9083023 pound per square inch | 220,000 pascal |
| Standard atmosphere | 14.69594878 pound per square inch | 101,325 pascal |
| Blood pressure (systolic) | 2.3206038 pound per square inch | 16,000 pascal |
| Deep-sea submersible | 15,954.15115032 pound per square inch | 110,000,000 pascal |
| Bicycle tyre | 89.92339739 pound per square inch | 620,000 pascal |
Available Pressure units
More pound per square inch conversions
- Convert pound per square inch to pascal
- Convert pound per square inch to kilopascal
- Convert pound per square inch to bar
- Convert pound per square inch to atmosphere
- Convert pound per square inch to millibar
- Convert pound per square inch to hectopascal
- Convert pound per square inch to torr
- Convert pound per square inch to inch of mercury
- Convert pound per square inch to megapascal