Pressure Calculator
Calculate pressure using P = Force ÷ Area, or use the unit converter to instantly convert between Pa, kPa, MPa, bar, psi, atm, mmHg, and more.
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Pressure Formula
The Pascal (Pa) is the SI unit of pressure, defined as one Newton per square metre (1 N/m²). It is a very small unit — standard atmospheric pressure is 101,325 Pa (101.325 kPa).
Frequently Asked Questions
Pressure is the force applied perpendicular to a surface per unit area. The SI unit is the Pascal (Pa), equal to 1 N/m². Pressure determines how much force is concentrated on a surface. A sharp needle exerts much greater pressure than a flat palm because the area is tiny, even with the same force applied.
Absolute pressure is the total pressure including atmospheric pressure. Gauge pressure is the pressure measured relative to atmospheric pressure (atmospheric = 0). Tire pressure is measured in gauge pressure: 30 psi gauge = 30 + 14.696 ≈ 44.7 psi absolute. Absolute pressure = gauge pressure + atmospheric pressure (101.325 kPa).
Multiply bar by 14.5038 to get psi. For example, 2 bar × 14.5038 = 29.01 psi. To convert psi to bar, divide by 14.5038 or multiply by 0.06895.
1 kPa = 1,000 Pa, and 1 MPa = 1,000,000 Pa (1,000 kPa). Pascals are used for very low pressures (sound). Kilopascals suit atmospheric and weather pressures. Megapascals are used in hydraulics and structural engineering.
mmHg stands for millimetres of mercury. It is the pressure exerted by a 1 mm column of liquid mercury under standard gravity. It was originally used in barometers. 1 mmHg ≈ 133.322 Pa. Standard atmospheric pressure = 760 mmHg. Blood pressure is still commonly measured in mmHg (e.g. 120/80 mmHg).
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