The pascal (symbol: Pa) is the SI derived unit of pressure, internal pressure, stress, Young s modules and tensile strength, defined as one newton per square metre. Pressure is a measure of force per unit area. It is named after the French mathematician, physicist, inventor, writer, and philosopher Blaise Pascal.
Common multiple units of the pascal are the hectopascal (1 hPa ≡ 100 Pa) which is equal to 1 mbar, the kilopascal (1 kPa ≡ 1000 Pa), the megapascal (1 MPa ≡ 1,000,000 Pa), and the gigapascal (1 GPa ≡ 1,000,000,000 Pa).
On Earth, standard atmosphere pressure is defined as 101.325 kPa. Meteorological barometric pressure reports typically report atmospheric pressure in hectopascals, corresponding to about 0.1% of atmospheric pressure. The main corresponding imperial and US customary unit is the pound per square inch (psi); in the context of meteorology, the inch of mercury may also be encountered.