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atm - Standard Atmosphere Pressure Unit
Standard Atmosphere is mainly used as a reference value for the average atmospheric pressure at sea level. It is often used to indicate the depth rating for a water resistant watch, but otherwise is rarely used as a unit for measuring pressure. 1 Standard Atmosphere is defined as being exactly equal to 101,325 Pascals.
Since the atmospheric presssure varies with changes in weather and altitude, it is convenient to standardise on a single value so that ratings, measurements and specifications can be compared. In particular 1 Standard Atmosphere is used by the Aviation industry as the reference standard for sea level pressure.
In the table below you will find the equivalent values for 1 atm in other pressure units.
To calculate the number of atmospheres for a pressure value in other units please click on the relevant unit link below.
For converting many readings to or from atmospheres please use our pressure unit calculator.
| 1.01325 | bar |
| 14.6959 | psi |
| 1013.25 | mbar |
| 101325 | N/m² |
| 101325 | Pa |
| 1013.25 | hPa |
| 101.325 | kPa |
| 0.101325 | MPa |
| 1.03323 | kg/cm² |
| 10332.3 | mmH2O 4°C (39.2°F) |
| 1033.23 | cmH2O 4°C (39.2°F) |
| 10.3323 | mH2O 4°C (39.2°F) |
| 406.782 | inH2O 4°C (39.2°F) |
| 33.8985 | ftH2O 4°C (39.2°F) |
| 760 | mmHg 0°C (32°F) |
| 76 | cmHg 0°C (32°F) |
| 29.9213 | inHg 0°C (32°F) |
| 760 | Torr |
| 760000 | mTorr |
| 1 | atm |
| 1.03323 | at |
| 1013250 | dyn/cm² |
| 235.135 | oz/in² |
| 760000 | µHg 0°C (32°F) |
| 0.00656069 | tsi (uk, long) |
| 0.00734797 | tsi (usa, short) |
| 1.05811 | tsf (usa, short) |
| 2116.22 | psf |
| 1033.23 | g/cm² |
Please note that the conversion factors above are accurate to 6 significant figures.
Site Last Updated: 09/02/12
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