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What is a atmosphere?

The standard reference atmospheric pressure — 101,325 Pa

Definition

The standard atmosphere equals 101,325 pascals exactly — defined by CGPM in 1954. Represents average sea-level atmospheric pressure. Used in chemistry, aviation and engineering as a reference pressure.

Common uses

  • Chemistry standard conditions
  • Aviation cockpit pressurisation references
  • Pressure tank and vessel ratings

🌍 Real-world scale

Sea-level pressure: 1 atm. Mount Everest summit: ~0.33 atm. Submarine at 100 m: ~11 atm.

Convert from atmospheres

9 conversions
Atmosphere to Pascal1 atm = 101,325 PaAtmosphere to Kilopascal1 atm = 101.325 kPaAtmosphere to Megapascal1 atm = 0.1013 MPaAtmosphere to Bar1 atm = 1.01325 barAtmosphere to Millibar1 atm = 1,013.25 mbarAtmosphere to Pound per Square Inch1 atm = 14.6959 psiAtmosphere to Millimeter of Mercury1 atm = 760 mmHgAtmosphere to Torr1 atm = 760 TorrAtmosphere to Inch of Mercury1 atm = 29.9213 inHg

Convert to atmospheres

9 conversions
Pascal to Atmosphere1 Pa = 9.8692e-6 atmKilopascal to Atmosphere1 kPa = 0.009869 atmMegapascal to Atmosphere1 MPa = 9.86923 atmBar to Atmosphere1 bar = 0.9869 atmMillibar to Atmosphere1 mbar = 0.0009869 atmPound per Square Inch to Atmosphere1 psi = 0.06805 atmMillimeter of Mercury to Atmosphere1 mmHg = 0.001316 atmTorr to Atmosphere1 Torr = 0.001316 atmInch of Mercury to Atmosphere1 inHg = 0.03342 atm

Tips

  • 1 atm = 101,325 Pa = 1.01325 bar = 14.696 psi.
  • Note: atm ≠ bar. Close but not identical.
  • Modern SI prefers pascals; atm is a legacy reference.

Common mistakes

  • Using 1 atm = 1 bar exactly — off by 1.3%.
  • Confusing standard atm with technical atmosphere (98,066.5 Pa) or atmosphere-absolute in diving.
  • Applying 1 atm outside sea level without correction.

FAQ about the atmosphere

What is a atmosphere?
The standard atmosphere equals 101,325 pascals exactly — defined by CGPM in 1954. Represents average sea-level atmospheric pressure. Used in chemistry, aviation and engineering as a reference pressure.
Where is the atmosphere used?
The atmosphere is commonly used for: Chemistry standard conditions; Aviation cockpit pressurisation references; Pressure tank and vessel ratings.
What is an example of a atmosphere in real life?
Sea-level pressure: 1 atm. Mount Everest summit: ~0.33 atm. Submarine at 100 m: ~11 atm.
What category does the atmosphere belong to?
The atmosphere is a unit of pressure, part of the 10-unit pressure category on UnitConv.
How accurate are atmosphere conversions?
All conversion factors follow NIST and BIPM international standards to 8 significant figures — the highest practical accuracy.
Explore all 10 pressure units and their conversions.🎈 Pressure hub →