Convert units and preserve the reference
- Enter the reading and select its source and target units.
- Choose whether the reading is absolute, gauge or differential.
- Convert and review the unchanged reference before copying or downloading.
Definitions and examples
One bar = 100 kPa = 100,000 Pa. One standard atmosphere (atm) = 101,325 Pa = 101.325 kPa. One hPa equals one mbar. One psi is approximately 6.894757 kPa. Factors follow NIST’s pressure table. The psi factor is calculated from the international pound, standard gravity and international inch.
| Unit | Pascals per unit |
|---|---|
| Pascals (Pa) | 1 |
| Hectopascals (hPa) | 100 |
| Kilopascals (kPa) | 1000 |
| Megapascals (MPa) | 1000000 |
| Bars (bar) | 100000 |
| Millibars (mbar) | 100 |
| Standard atmospheres (atm) | 101325 |
| Pounds-force per square inch (psi) | 6894.757293168361 |
Absolute, gauge and differential
Absolute pressure uses a vacuum reference and must be nonnegative. Gauge pressure is relative to the ambient reference; differential pressure is a difference between two pressures. Signed gauge/differential readings are allowed. For example −1 bar gauge becomes −100 kPa gauge.
The chosen reference is preserved. Converting a gauge reading to an absolute reading requires a known reference pressure, which this tool does not add or assume. A standard atmosphere is a unit definition, not a measurement of current ambient pressure. Signed readings are not checked for physical consistency with an unknown reference.
Limits and privacy
Source magnitude up to 10¹⁵; negative absolute input rejected, tiny arithmetic underflow rejected. No gauge-to-absolute transformation, calibration, altitude/weather estimation, mercury/water-column variants or instrument assessment. Display uses up to 12 significant digits and six decimal places or scientific notation. CSV retains numeric floating-point values and the selected reference.
Inputs stay in browser memory without requests, uploads or saved readings. Live conversion updates after a 300 ms pause. Every supported unit can be compared and exported with its reference. Swap keeps the number and exchanges units; Use result preserves the raw calculated quantity and reverses direction. Examples, swaps, result reuse and Reset offer one Undo step, including the selected reference. Editing inputs clears that action history. Reset clears results and restores 1 bar absolute to kPa.
Does converting psi into bar change gauge pressure to absolute?
No. A change of unit preserves the reference; changing the reference is a separate calculation.