1 atmosphere equals exactly
101.325 Pa
The standard atmosphere (atm) is a pressure unit historically defined to represent the average atmospheric pressure at sea level. Its exact value, 101,325 Pa, was set by international convention and is used as a reference in many scientific and technical calculations.
To convert a measurement from atmospheres to Pascal, simply multiply the value by 101,325:
To convert from Pascal to atmospheres, perform the inverse operation, dividing by 101,325:
This conversion is useful in physics and chemistry, where the atmosphere is still used as an intuitive reference unit (for example to describe standard temperature and pressure conditions, STP), but formulas and calculations often require the corresponding value in Pascal, the official SI unit.