Pressure Converter
This converter changes a numerical pressure value between pascals (Pa), kilopascals (kPa), megapascals (MPa), bar, pounds per square inch (psi), kilopounds per square inch (ksi), standard atmosphere (atm), hectopascals (hPa), millibar (mbar), Torr, and millimetres of mercury (mmHg).
It performs a unit conversion only. It does not decide whether the input is gauge pressure, absolute pressure, differential pressure, or a weather-station value.
Method used
Each supported unit has a factor in pascals. The converter first changes the input to Pa and then divides by the target unit's Pa factor:
target value = input value × source factor ÷ target factor
The principal factors used by the tool include:
| Unit | Pascals used by SoupCalc |
|---|---|
1 kPa |
1,000 Pa |
1 bar |
100,000 Pa |
1 psi |
6,894.757293 Pa |
1 atm |
101,325 Pa |
1 hPa or 1 mbar |
100 Pa |
1 Torr |
101,325 ÷ 760 Pa |
1 mmHg |
approximately 133.322387415 Pa |
The pascal is the SI derived unit equal to one newton per square metre. SoupCalc keeps more precision internally than it may display.
Worked example
Convert 30 psi to kPa:
- Convert to pascals:
30 × 6,894.757293168 = 206,842.718795... Pa. - Divide by
1,000 Pa/kPa:206,842.718795... ÷ 1,000 = 206.842718795... kPa.
The result is approximately 206.843 kPa. The reverse conversion returns 30 psi apart from ordinary floating-point display rounding.
As a second reference identity, 760 Torr = 1 atm under the definition used here because one Torr is one 760th of a standard atmosphere.
How to interpret the result
The converted number represents the same pressure magnitude expressed in a different unit. Preserve the original measurement type in your notes: for example, 30 psig and 30 psia are not interchangeable merely because both use psi.
Round the result only as far as the measurement and task justify. Extra digits from a converter do not add accuracy to a gauge, sensor, forecast, or source value.
Limits of the conversion
Gauge pressure is measured relative to local ambient pressure; absolute pressure is measured relative to a vacuum. Converting units does not add or subtract atmospheric pressure. To change between gauge and absolute pressure, you need the applicable ambient pressure and a separate physical calculation.
Mercury-column units can also depend on their defining convention, density, gravity, and temperature. Torr and mmHg are close but are represented separately here; they should not be assumed identical in high-precision work. Use the conversion factors and standards required by your laboratory, engineering code, regulator, or instrument documentation.
This tool does not include uncertainty propagation, calibration correction, altitude adjustment, sensor linearization, or safety limits. Verify critical engineering, medical, diving, aviation, and process-control calculations with qualified procedures and calibrated equipment.
Sources
- NIST — Pressure and Gas Flow Unit Conversions
- NIST Guide to the SI, Appendix B — Conversion Factors
- NIST Guide to the SI, Chapter 4 — Derived units including the pascal
- BIPM — The International System of Units (SI Brochure)
Editorial record
Written and manually reviewed by the SoupCalc Editorial Team. Conversion factors and worked examples were checked against the current unit registry and automated tests. Last reviewed: August 10, 2026. This page remains unavailable for indexing and advertising until all approved localizations pass review.