Atmospheres
The atmosphere (atm) is a unit of pressure being equal to 101,325 pascals. It is based on the average atmospheric pressure at sea level on Earth.
Pascals
Pascals (Pa) are the SI units of pressure named after the French mathematician Blaise Pascal. It is defined as one newton per square meter (N/m²). Since the pascal is a relatively small unit, kilopascals (kPa), megapascals (MPa), and gigapascals (GPa) are often used for practical applications.