Pressure Conversion
Pressure measurement units
Required Parameters
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Quick Answer
1 atm = 101.325 kPa = 14.696 psi = 1.01325 bar = 760 mmHg. Use gauge pressure (PSIG) for most industrial applications and absolute pressure (PSIA) for vacuum and thermodynamic calculations.
Pressure Conversion Calculator
Convert between pressure units: Pascal, bar, psi, atm, mmHg, and Torr.
Key Conversions
- 1 atm = 101,325 Pa = 1.01325 bar = 14.696 psi = 760 mmHg
Design Notes
Pressure sensing in electronics uses MEMS sensors calibrated in Pa or PSI. Common full-scale ranges: 100 Pa (HVAC), 100 kPa (barometric), 700 kPa (tire/pneumatic), 35 MPa (hydraulic). Always specify gauge vs absolute.
Common Mistakes
- 1
Confusing gauge pressure (relative to atmosphere) with absolute pressure (relative to vacuum).
- 2
Using 1 bar = 1 atm as an approximation when precision matters (1 bar = 100 kPa, 1 atm = 101.325 kPa).
- 3
Forgetting to specify PSIG vs PSIA — the 14.7 psi difference matters for calculations.
Knowledge Base
What is 1 bar in kPa?
1 bar = 100 kPa exactly. 1 bar is slightly less than 1 standard atmosphere (1 atm = 101.325 kPa). The bar is widely used in European industrial applications, meteorology, and tire pressure specifications.
What is 1 atm in PSI?
1 atmosphere = 14.696 psi = 101.325 kPa = 1.01325 bar = 760 mmHg = 29.92 inHg. This is standard atmospheric pressure at sea level. For quick conversion: 1 atm ≈ 15 psi ≈ 100 kPa ≈ 1 bar.
What is PSI?
Pounds per Square Inch — the US customary pressure unit. 1 PSI = 6.895 kPa. Used for tire pressure (typically 30-35 PSI for cars), compressed air systems (90-150 PSI), and hydraulic systems (3000-5000 PSI). PSIG means gauge pressure (relative to atmospheric); PSIA means absolute pressure.
What is the difference between gauge and absolute pressure?
Absolute pressure is measured from true zero (perfect vacuum). Gauge pressure is measured from atmospheric pressure. P_absolute = P_gauge + P_atmospheric. Example: a tire at 32 PSIG = 32 + 14.7 = 46.7 PSIA. Vacuum measurements use negative gauge pressure.
What is a Pascal?
The SI unit of pressure: 1 Pa = 1 N/m². It is very small — normal atmospheric pressure is 101,325 Pa. In practice, kilopascals (kPa) or megapascals (MPa) are used. 1 kPa = 1000 Pa. 1 MPa = 1,000,000 Pa = 145 psi. Material yield strengths are typically in MPa.
What is mmHg (Torr)?
Millimeters of mercury, also called Torr. 1 atm = 760 mmHg. Used in medical blood pressure readings (e.g., 120/80 mmHg), vacuum technology, and barometric pressure. Named after Evangelista Torricelli who invented the mercury barometer. 1 mmHg = 133.322 Pa.
What pressure units are used in HVAC?
HVAC uses inches of water column (inWC or inH2O) for duct pressure (typically 0.5-2 inWC), PSI for refrigerant pressures (50-400 PSI), and Torr or microns for vacuum measurements. 1 inWC = 248.84 Pa = 0.036 PSI.
How do I convert bar to PSI?
Multiply bar by 14.504. Example: 2.5 bar = 2.5 × 14.504 = 36.26 PSI. Reverse: PSI × 0.06895 = bar. Quick approximation: 1 bar ≈ 14.5 PSI. Tire pressure: 2.2 bar = 32 PSI, 2.5 bar = 36 PSI, 2.8 bar = 41 PSI.
What is vacuum pressure?
Vacuum means pressure below atmospheric. Perfect vacuum = 0 Pa absolute. Common vacuum levels: rough vacuum (1-1000 Pa), medium vacuum (0.1-1 Pa), high vacuum (10⁻⁷-0.1 Pa), ultra-high vacuum (below 10⁻⁷ Pa). Electronics use vacuum for sputtering, evaporation coating, and electron beam processing.
What pressure is used in semiconductor manufacturing?
Wafer fabrication uses extreme vacuum: sputtering at 0.1-10 Pa, CVD at 10-1000 Pa, ion implantation at 10⁻⁴-10⁻² Pa. Cleanroom air is typically maintained at slight positive pressure (2-5 Pa above ambient) to prevent particle infiltration.