atmosphere (atm)
1 atmosphere = 101,325 pascals
What is atmosphere?
An atmosphere (atm) is a pressure unit equal to mean atmospheric pressure at sea level, approximately 101,325 pascals. It is used as a reference in chemistry, diving tables, and altitude calculations.
Notes: Standard atmosphere
Real-world uses
Atmospheres are used as a reference pressure in chemistry (standard conditions: 1 atm, 25°C), scuba diving (each 10 m of seawater adds about 1 atm), and high-pressure industrial applications like autoclaves and pressure vessels.
History
The standard atmosphere was originally defined as the pressure exerted by a 760 mm column of mercury at 0°C under standard gravity. Evangelista Torricelli first measured atmospheric pressure in 1644 using a mercury barometer, establishing this foundational concept.
Common mistakes
Confusing standard atmosphere (101,325 Pa) with technical atmosphere (1 kgf/cm² ≈ 98,066.5 Pa). Also, assuming atmospheric pressure is constant at 1 atm everywhere—it varies with altitude, weather, and temperature.
When is this conversion used?
Tyre pressure gauges, HVAC systems, and industrial equipment may use different pressure units depending on the manufacturer and region. Converting between psi, bar, and kPa is common in automotive and engineering work.
How to convert atmosphere to pascal
To convert atmosphere to pascal, multiply the value by 101,325.
Conversion formula (from base unit)
x * 101325.0
Measurement standards
The pascal (Pa) is the SI derived unit of pressure, defined as one newton per square metre. The World Meteorological Organization mandates the hectopascal (hPa) for atmospheric pressure reporting in aviation and weather services.
Did you know?
The pressure at the bottom of the Mariana Trench, nearly 11 km deep, exceeds 1,086 bar — over a thousand times atmospheric pressure. At this depth, water is compressed by about 5%, making it measurably denser than at the surface.
| atmospheres | pascals |
|---|---|
| 0.1 | 10,132.5 |
| 0.5 | 50,662.5 |
| 1 | 101,325 |
| 2 | 202,650 |
| 5 | 506,625 |
| 10 | 1,013,250 |
| 25 | 2,533,125 |
| 50 | 5,066,250 |
| 100 | 10,132,500 |
| 250 | 25,331,250 |
| 500 | 50,662,500 |
| 1,000 | 101,325,000 |
Common values
| atmospheres | pascals | |
|---|---|---|
| Car tyre | 2.17123119 atmospheres | 220,000 pascals |
| Standard atmosphere | 1 atmosphere | 101,325 pascals |
| Blood pressure (systolic) | 0.15790772 atmospheres | 16,000 pascals |
| Deep-sea submersible | 1,085.61559339 atmospheres | 110,000,000 pascals |
| Bicycle tyre | 6.11892425 atmospheres | 620,000 pascals |
Full atmosphere conversion table
| Unit | Value | Factor |
|---|---|---|
| pascal | 1 atm = 101,325 Pa | × 101,325 |
| kilopascal | 1 atm = 101.325 kPa | × 101.325 |
| bar | 1 atm = 1.01325 bar | × 1.01325 |
| pound per square inch | 1 atm = 14.69594878 psi | × 14.69594878 |
| millibar | 1 atm = 1,013.25 mbar | × 1,013.25 |
| hectopascal | 1 atm = 1,013.25 hPa | × 1,013.25 |
| torr | 1 atm = 760 Torr | × 760 |
| inch of mercury | 1 atm = 29.9212524 inHg | × 29.9212524 |
| megapascal | 1 atm = 0.101325 MPa | × 0.101325 |