- SI unit of pressure, equal to one newton per square meter
- named after Blaise Pascal, pioneer of fluid mechanics and probability
- atmospheric pressure at sea level: ~101325 Pa = 1 atm = 1013.25 hPa
- hectopascal (hPa) used in meteorology, equivalent to 1 millibar
- kilopascal (kPa) common in engineering: tire pressure ~200-250 kPa
- gigapascal (GPa) measures material hardness and tectonic stress
- Pascal’s principle: pressure applied to a confined fluid transmits equally in all directions
- blood pressure reported in mmHg but convertible to kPa (1 mmHg = 133.3 Pa)