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 kilopascal?
A kilopascal is a metric pressure unit equal to 1,000 pascals. It is used for weather forecasts, tire pressure specifications in metric countries, and structural and mechanical engineering calculations.
Real-world uses
Kilopascals are used for tyre pressure in most countries (standard car tyres are about 200–250 kPa), blood pressure in some medical systems, and hydraulic system specifications. Atmospheric pressure at sea level is approximately 101.325 kPa.
History
The kilopascal became a practical engineering unit with the adoption of the SI system. It offers a convenient scale for everyday pressure measurements, bridging the gap between the tiny pascal and the larger bar or atmosphere.
Common mistakes
Confusing kPa with psi when checking tyre pressure. 1 psi ≈ 6.895 kPa, so 32 psi ≈ 220 kPa. Inflating a tyre to 32 kPa instead of 220 kPa would leave it nearly flat.
When is this conversion used?
Converting between pound per square inch and kilopascal 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 = 6.89475729 kilopascal
1 kilopascal = 1,000 pascal
How to convert pound per square inch to kilopascal
To convert pound per square inch to kilopascal, multiply the value by 6.89475729.
To convert kilopascal back to pound per square inch, multiply by 0.14503774.
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 kilopascal
| pound per square inch | kilopascal |
|---|---|
| 0.1 | 0.68947573 |
| 0.5 | 3.44737865 |
| 1 | 6.89475729 |
| 2 | 13.78951459 |
| 5 | 34.47378647 |
| 10 | 68.94757293 |
| 25 | 172.36893233 |
| 50 | 344.73786466 |
| 100 | 689.47572932 |
| 250 | 1,723.68932329 |
| 500 | 3,447.37864658 |
| 1,000 | 6,894.75729317 |
Common values
| pound per square inch | kilopascal | |
|---|---|---|
| Car tyre | 31.9083023 pound per square inch | 220 kilopascal |
| Standard atmosphere | 14.69594878 pound per square inch | 101.325 kilopascal |
| Blood pressure (systolic) | 2.3206038 pound per square inch | 16 kilopascal |
| Deep-sea submersible | 15,954.15115032 pound per square inch | 110,000 kilopascal |
| Bicycle tyre | 89.92339739 pound per square inch | 620 kilopascal |
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