Atmospheres (atm)
One atmosphere (atm) is a unit of pressure defined as exactly 101,325 pascals (Pa). It approximates the average air pressure at sea level on Earth. The atmosphere unit is used for expressing pressures in meteorology and engineering [iso-80000].
Origin
The atmosphere was originally defined in the 19th century based on average sea-level air pressure. It was standardized by the International Union of Pure and Applied Chemistry (IUPAC) and other bodies to equal 101,325 Pa in the mid-20th century [nist-sp-811].
Worldwide Use
Atmospheres are used worldwide in scientific fields, including chemistry and physics, and in engineering applications like pressure vessel design. It is less common in everyday use outside these fields [nist-sp-811].
Common References
- Standard atmospheric pressure at sea level is 1 atm
- A typical car tire pressure is about 2 atm
- Deep-sea diving pressures can exceed 10 atm
Atmospheres → Pascals1 atm = 101,325 PaAtmospheres → Kilopascals1 atm = 101.325 kPaAtmospheres → Megapascals1 atm = 0.1013 MPaAtmospheres → Hectopascals1 atm = 1,013.25 hPaAtmospheres → Bars1 atm = 1.0133 barAtmospheres → Millibars1 atm = 1,013.25 mbarAtmospheres → Torr1 atm = 760.0021 TorrAtmospheres → Millimeters of Mercury1 atm = 760.0021 mmHgAtmospheres → Pounds per Square Inch1 atm = 14.6959 psiAtmospheres → Kilopounds per Square Inch1 atm = 0.0147 ksiAtmospheres → Inches of Mercury1 atm = 29.9213 inHgAtmospheres → Inches of Water1 atm = 406.7937 inH₂O