Common pressure units
Pascal is the SI unit of pressure. Kilopascals, bar, PSI, standard atmospheres and millimeters of mercury are also common in engineering, weather, automotive and medical contexts.
Use the correct context
Always preserve the original unit and context when a pressure value is used for a regulated or safety-sensitive application.
Common Pressure Units
Pascal (Pa) is the SI unit of pressure. Common related units include kilopascal (kPa), bar, pounds per square inch (PSI), standard atmosphere (atm) and millimeters of mercury (mmHg).
Useful Reference Relationships
- 1 bar = 100 kPa.
- 1 standard atmosphere = 101.325 kPa.
- 1 PSI is approximately 6.894757 kPa.
- 1 mmHg is approximately 0.133322 kPa.
Why the Application Matters
The same numerical pressure can be expressed in several units, but the correct unit depends on the application. Automotive, weather, engineering and medical contexts may use different conventions.
Worked Example
To convert 2 bar to kilopascals, multiply by 100. The result is 200 kPa. For a reverse conversion, divide the kilopascal value by 100.
Pressure Unit Checklist
- Identify the source pressure unit.
- Confirm the destination unit.
- Check whether the specification uses gauge or absolute pressure.
- Apply the correct conversion relationship.
- Round only after the calculation.
- For safety-sensitive work, verify the result against the applicable standard.
Use the Tervilo Pressure Converter
Use the Tervilo Pressure Converter for Pa, kPa, bar, PSI, atm and mmHg conversions.
Understanding Common Pressure Units
Pressure describes force distributed over an area. Different industries use different pressure units, so identifying both the source and target unit is essential before performing a conversion.
Common Pressure Units
| Unit | Common Context |
|---|---|
| Pa | SI base pressure unit |
| kPa | Engineering, weather and technical measurements |
| bar | Industrial and technical applications |
| psi | Tyres, equipment and US customary measurements |
| atm | Reference to standard atmospheric pressure |
| mmHg | Pressure measurements in specific scientific and technical contexts |
Useful Pressure Relationships
Some commonly used relationships are:
- 1 kPa = 1,000 Pa
- 1 bar = 100 kPa
- 1 atm = 101.325 kPa
- 1 psi is approximately 6.89476 kPa
These relationships should be treated as conversion definitions or standard reference relationships according to the target application. Always use the precision required by the measurement.
Why Pressure Conversion Requires Care
Pressure values can represent very different scales even when the numerical values look similar. A value expressed in psi cannot be interpreted as kPa without conversion. The same applies to bar, atm, Pa and other pressure units.
Worked Conversion Example
To convert 2 bar to kilopascals, multiply by 100:
To convert a pressure from kPa to bar, divide by 100.
Absolute and Gauge Pressure
Some technical applications distinguish absolute pressure from gauge pressure. A pressure conversion between units does not automatically change the reference point. If a specification uses gauge pressure, preserve that context when interpreting or comparing the result.
Common Pressure Conversion Mistakes
- Confusing Pa with kPa.
- Using a pressure conversion factor in the wrong direction.
- Ignoring whether a value is gauge or absolute pressure.
- Rounding a pressure value before completing a multi-step calculation.
- Assuming every pressure unit is used in the same industry or context.
Practical Uses
Pressure conversion is useful for tyres, industrial equipment, engineering specifications, weather information, technical documentation and measurements that use different pressure standards.
Use the Tervilo Pressure Converter
Select the exact source and target pressure units before converting. For technical work, retain sufficient precision and preserve the original pressure context when comparing measurements.