Convert between 13 pressure units: Pa, kPa, MPa, bar, atm, PSI, mmHg, inHg, cmH₂O, kg/cm², and more with batch mode and context table.
Pressure is one of the most over-unitized quantities in science and engineering. Between Pascals, PSI, bar, atmospheres, mmHg, inches of mercury, centimeters of water, and technical atmospheres, even experienced engineers occasionally need to look up conversion factors. Different industries stubbornly prefer their own units — HVAC uses inches of water for duct pressure, tire shops use PSI, meteorologists use hectopascals, and hydraulics engineers use bar or MPa.
This converter supports 13 pressure units with instantaneous cross-conversion. Enter a value in any unit and see all 13 equivalents at once, plus a real-world context indicator that tells you where your pressure sits on the scale from perfect vacuum to diamond anvil cell. Batch conversion handles bulk datasets, and the context table gives intuitive scale for pressures from weather systems to industrial hydraulics.
Whether you're checking tire pressure, calibrating sensors, converting lab data, or translating between US customary and SI units, this tool covers every pressure unit you'll encounter in practice.
Pressure has more unit systems than almost any other physical quantity. This converter handles all 13 common units, shows all equivalents at once, and includes real-world context so you can sanity-check your values against known pressures. Keep these notes focused on your operational context. Tie the context to the calculator’s intended domain. Use this clarification to avoid ambiguous interpretation.
All conversions go through Pascals (Pa) as the intermediate unit. value_out = value_in × (factor_in ÷ factor_out) Key factors: 1 atm = 101,325 Pa 1 PSI = 6,894.757 Pa 1 bar = 100,000 Pa 1 mmHg = 133.322 Pa 1 inHg = 3,386.389 Pa
Result: 2.0684 bar
30 PSI × 6,894.757 Pa/PSI ÷ 100,000 Pa/bar = 2.0684 bar. This is about 2 atmospheres gauge — typical car tire pressure.
**SI family**: Pa, hPa, kPa, MPa, GPa — related by powers of 10. Used in science, engineering, and internationally.
**US customary**: PSI (PSIA for absolute, PSIG for gauge) — dominant in US automotive, HVAC, and industrial applications.
**Barometric**: mbar/hPa (meteorology), mmHg/Torr (medicine, vacuum), inHg (US weather reports, aviation).
**Water column**: cmH₂O, inH₂O — used in HVAC, respiratory medicine, and low-pressure measurement.
Pressure instruments may read "gauge pressure" (relative to atmospheric) or "absolute pressure" (relative to perfect vacuum). At sea level, absolute = gauge + 101,325 Pa (≈14.7 PSI). Always clarify which reference is used — mixing them up is a common and dangerous error in engineering.
The Torr was named after Evangelista Torricelli, who invented the mercury barometer in 1643. The atmosphere was originally defined as the pressure needed to support 760 mm of mercury. Modern definitions are based on the Pascal (1 N/m²), named after Blaise Pascal, who demonstrated atmospheric pressure with his famous barrel experiment.
1 atm = 101,325 Pa = 14.696 PSI = 1.01325 bar = 760 mmHg = 29.92 inHg. This is defined as sea-level pressure at 15 °C.
PSI is absolute pressure; PSIG (PSI gauge) is pressure above atmospheric. A tire at 32 PSIG is 32 + 14.7 = 46.7 PSIA.
Hectopascals (hPa) are numerically identical to millibars (mbar), which meteorology has used since the mid-20th century. 1 hPa = 100 Pa = 1 mbar.
mmHg (millimeters of mercury) is traditional in blood pressure readings, vacuum systems, and barometers. 1 mmHg ≈ 1 Torr.
A technical atmosphere (at) equals the pressure of 1 kgf per cm². It is 98,066.5 Pa — close to, but not equal to, a standard atmosphere (101,325 Pa).
Nearly — 1 bar = 100,000 Pa while 1 atm = 101,325 Pa. The difference is about 1.3%, but it matters in precise work.