Supported units
- Pascal (Pa)
- Kilopascal (kPa)
- Megapascal (MPa)
- Bar
- Pound per square inch (psi)
- Standard atmosphere (atm)
Conversion tool
Pressure Converter
Select a category, enter a value, and convert between compatible units.
Pressure units explained
Pressure is force distributed over an area. Pascals, kilopascals, megapascals, bar and psi are frequently used in engineering specifications and fluid systems.
Common engineering uses
Pressure conversion is used in hydraulics, pneumatics, pumps, compressors and process engineering. Gauge and absolute pressure references should not be confused.
Formula
P = F / A
Pressure equals the force acting perpendicular to a surface divided by the area over which that force is distributed. In SI units, one pascal equals one newton per square metre.
- P = pressure, measured in pascals (Pa)
- F = perpendicular force, measured in newtons (N)
- A = area, measured in square metres (m²)
Common conversions
| From | Equivalent value |
|---|---|
| 1 kilopascal (kPa) | 1,000 pascals (Pa) |
| 1 megapascal (MPa) | 1,000 kPa = 10 bar |
| 1 bar | 100 kPa ≈ 14.5038 psi |
| 1 psi | 6.89476 kPa |
| 1 standard atmosphere (atm) | 101.325 kPa ≈ 1.01325 bar ≈ 14.6959 psi |
Convert 250 kPa to psi
- Use the relationship 1 psi = 6.89476 kPa.
- Divide the pressure in kPa by 6.89476.
- 250 / 6.89476 = 36.2594 psi.
250 kPa ≈ 36.26 psi
The final value is rounded to two decimal places. Keep additional digits when the result will be used in a subsequent engineering calculation.
Engineering applications
- Hydraulic systems, including cylinders, pumps and pressure-relief settings.
- Pneumatic systems, compressors, air tools and control equipment.
- HVAC and refrigeration systems, including refrigerant and duct-pressure measurements.
- Automotive applications such as tyre pressure, fuel systems and engine testing.
- Process engineering, piping, pressure vessels and instrumentation.
Common mistakes
- Confusing gauge pressure with absolute pressure. A unit conversion does not change the pressure reference.
- Missing metric prefixes: 1 MPa equals 1,000 kPa and 1,000,000 Pa.
- Treating pressure as force. Pressure depends on both the applied force and the area.
- Using an area value in mm² or cm² while applying a formula that expects m².
- Rounding intermediate values too early, which can reduce the accuracy of later calculations.
Frequently asked questions
How many kilopascals are in one bar?
One bar equals exactly 100 kilopascals, or 100,000 pascals.
How many psi are in one bar?
One bar is approximately 14.5038 psi.
What is the difference between gauge and absolute pressure?
Gauge pressure is measured relative to the local atmospheric pressure. Absolute pressure is measured relative to a perfect vacuum.
What is the SI unit of pressure?
The SI unit is the pascal (Pa), defined as one newton per square metre.
Does converting pressure units change gauge pressure into absolute pressure?
No. Unit conversion changes only the unit. Converting between gauge and absolute pressure also requires the relevant atmospheric pressure.