Convert between atmospheres (atm) and Pascals (Pa). Bidirectional converter with kPa, hPa, mbar, and bar outputs, reference table, and preset values.
The atmosphere (atm) and the Pascal (Pa) are two of the most fundamental pressure units in science and engineering. One standard atmosphere is defined as exactly 101,325 Pascals. The Pascal, named after Blaise Pascal, is the SI unit of pressure equal to one newton per square meter. While the atm is convenient for expressing pressures relative to sea-level conditions, the Pascal is required for SI calculations in physics and engineering.
This converter lets you move seamlessly between atm and Pascals in either direction. It also shows derived units — kilopascals (kPa), hectopascals (hPa), millibars (mbar), and bar — because these are frequently encountered in meteorology, engineering specifications, and laboratory work.
Whether you are solving gas law problems in chemistry class, reading a weather map in hectopascals, or designing equipment rated in Pascals, this tool gives you instant, exact results without memorizing conversion factors across formulas, reports, and technical documentation. It is particularly useful when a problem statement explains pressure in atmospheres but the equation, sensor, or specification you are working with expects raw Pascals or kilopascals.
The exact conversion factor of 101,325 is not an easy number to multiply or divide mentally. This calculator handles it instantly and also shows related units (kPa, hPa, mbar, bar) so you don't need separate converters. It is essential for chemistry students, meteorologists, and engineers working across unit systems in labs and production settings.
ATM to Pascals: Pa = atm × 101,325 Pascals to ATM: atm = Pa ÷ 101,325 ATM to kPa: kPa = atm × 101.325 ATM to hPa: hPa = atm × 1,013.25 ATM to bar: bar = atm × 1.01325
Result: 101,325 Pa
1 atm is defined as exactly 101,325 Pascals (Pa). This is the standard atmospheric pressure at sea level used in chemistry and physics as a reference condition.
The Pascal was adopted as the SI unit of pressure in 1971, replacing the older CGS unit of barye. It is defined as one newton per square meter (N/m²). Because atmospheric pressure is over 100,000 Pa, derived units like kPa and hPa are more practical for everyday measurements.
Standard Temperature and Pressure (STP) in chemistry is defined as 0°C and 1 atm (101,325 Pa). Standard Ambient Temperature and Pressure (SATP) uses 25°C and exactly 1 bar (100,000 Pa). The distinction matters when doing precise molar volume calculations.
Meteorologists report pressure in hPa or mbar (identical units). Normal sea-level pressure is about 1013.25 hPa, and weather systems can range from about 870 hPa (extreme typhoons) to 1084 hPa (record high pressure). Engineers specify pneumatic and hydraulic pressures in kPa, bar, or psi depending on the region.
1 standard atmosphere equals exactly 101,325 Pascals. This is an exact definition adopted by the General Conference on Weights and Measures. It is equivalent to 101.325 kPa or 1,013.25 hPa.
A Pascal (Pa) is the SI unit of pressure, defined as one newton of force per square meter of area. It is named after Blaise Pascal, the French mathematician who pioneered research on fluid pressure in the 17th century.
The Pascal is the SI standard unit, making it consistent with other SI units (newtons, meters, joules). Using Pascals in equations like PV = nRT avoids extra conversion factors. Atmospheres are convenient for conceptualizing pressure but not for precise SI calculations.
They are all Pascals with different SI prefixes. 1 kPa = 1,000 Pa (kilo = thousand). 1 hPa = 100 Pa (hecto = hundred). Kilopascals are common in engineering; hectopascals are the standard in meteorology.
No, but they are close. 1 bar = 100,000 Pa while 1 atm = 101,325 Pa. The difference is about 1.3%. In casual use they are sometimes treated as interchangeable, but for precise work the distinction matters.
Divide the kPa value by 101.325. For example, 200 kPa ÷ 101.325 = 1.974 atm. Alternatively, multiply by 0.009869 to get atm.