Convert between pressure units: Pascals, PSI, Bar, Atmosphere, Torr, and more. Essential for physics, engineering, weather, and automotive applications.
Last updated: March 2026 | By Workshelve Team
Pressure is the force applied perpendicular to the surface of an object per unit area. It's measured as force divided by area, typically in Pascals (Pa) in the SI system, where 1 Pascal equals 1 Newton per square meter (N/m²).
Different fields use different pressure units based on tradition and convenience. Engineers often use PSI (pounds per square inch), meteorologists use millibars or hectopascals, scientists use Pascals or atmospheres, and medical professionals use mmHg (Torr) for blood pressure. Understanding conversions between these units is essential for cross-disciplinary work.
Standard atmospheric pressure at sea level is defined as 1 atmosphere (atm), which equals 101,325 Pascals, 14.696 PSI, or 760 mmHg. This is the baseline pressure exerted by Earth's atmosphere and serves as a reference point for many pressure measurements.
Converting tire pressure from PSI to Bar:
32 PSI (typical car tire pressure) equals approximately 2.21 bar or 220.6 kPa. European tire pressure gauges typically show bar, while American gauges show PSI.
Standard atmospheric pressure at sea level is 1 atm = 101,325 Pa = 101.325 kPa = 1.01325 bar = 14.696 PSI = 760 mmHg (Torr). This is the average pressure of Earth's atmosphere.
PSI by itself does not specify the pressure reference. PSIA denotes absolute pressure, while PSIG denotes gauge pressure relative to local atmospheric pressure. A tire at 32 PSIG is about 46.7 PSIA when local atmospheric pressure is about 14.7 psi.
Different fields developed their own units based on convenience and tradition. Engineers use PSI, meteorologists use millibars, scientists use Pascals, and medical professionals use mmHg. Each makes sense in its context.
A Pascal (Pa) is the SI unit of pressure, defined as 1 Newton per square meter (N/m²). It's named after Blaise Pascal. 1 Pa is very small, so kilopascals (kPa) and megapascals (MPa) are more common.
Torr and mmHg are very close and are often used interchangeably in practice. Torr is defined as exactly 1/760 of a standard atmosphere; mmHg is based on the pressure produced by a millimeter of mercury and is not exactly identical to the torr.
1 bar = 100,000 Pa = 100 kPa = 0.987 atm = 14.504 PSI. Bar is commonly used in European automotive and engineering applications. It's close to, but not exactly, atmospheric pressure.
Absolute pressure measures total pressure including atmospheric pressure (zero = perfect vacuum). Gauge pressure measures pressure above atmospheric (zero = atmospheric pressure). Most gauges show gauge pressure.
Most passenger car tires are 30-35 PSI (2.1-2.4 bar). Check your car's door jamb sticker for the exact specification. Tire pressure varies with temperature check when tires are cold.
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