How this pressure converter works
Every unit you select is first converted to pascal (Pa), the SI unit of pressure. Then we convert from pascal to all the other units shown in the panel. This is the same strategy used by lab-grade conversion references, and it keeps cross-system math consistent.
Formulas
Pa = value × factorToPa[sourceUnit]
target = Pa ÷ factorToPa[targetUnit]
Example: 25 psi → bar:
25 × 6894.757 = 172,368.925 Pa
172,368.925 ÷ 100,000 = 1.7237 bar
What are the most used pressure units?
- Pa / kPa / MPa: SI, engineering, hydraulics.
- bar / mbar: industry, weather, scuba.
- psi: US industry, tyres, hydraulics.
- atm: chemistry, thermodynamics.
- torr / mmHg: vacuum, lab instruments.
- inHg / inH₂O: HVAC, weather, duct testing.
FAQ
1. Why are torr and mmHg the same here?
Modern practice often uses 1 torr = 133.322368 Pa, exactly matching 1 mmHg at 0 °C. For vacuum and lab work this is fine, and it keeps the tool simple.
2. Can I do gauge vs absolute here?
This page converts units directly (absolute-style). To convert gauge to absolute you must add ambient atmospheric pressure before converting.
3. Are these definitions NIST-compatible?
Yes, the constants above follow commonly published NIST/NMI values and are suitable for engineering calculators.