Atmospheres to Pascals
Quick answer: 1 atm = 101,325 Pa. To convert, multiply the atm value by 101,325; to go back, divide.
The standard atmosphere is defined as exactly 101,325 pascals (101.325 kPa, 1.01325 bar, 14.696 psi), so converting is a single multiplication and the result is exact. Atmospheres are the everyday unit of diving, pressure cookers and chemistry; pascals are the SI unit used in engineering and weather.
The formula
Pa = atm × 101,325 · atm = Pa ÷ 101,325
Common values
| atm | Pa | also |
|---|---|---|
| 0.5 atm | 50,662.5 Pa | 50.663 kPa · 0.5066 bar · 7.35 psi |
| 1 atm | 101,325 Pa | 101.325 kPa · 1.0132 bar · 14.7 psi |
| 1.5 atm | 151,987.5 Pa | 151.988 kPa · 1.5199 bar · 22.04 psi |
| 2 atm | 202,650 Pa | 202.65 kPa · 2.0265 bar · 29.39 psi |
| 2.5 atm | 253,312.5 Pa | 253.313 kPa · 2.5331 bar · 36.74 psi |
| 3 atm | 303,975 Pa | 303.975 kPa · 3.0397 bar · 44.09 psi |
| 4 atm | 405,300 Pa | 405.3 kPa · 4.053 bar · 58.78 psi |
| 5 atm | 506,625 Pa | 506.625 kPa · 5.0663 bar · 73.48 psi |
| 10 atm | 1,013,250 Pa | 1,013.25 kPa · 10.1325 bar · 146.96 psi |
2.5 atm to Pa: 253,312.5 Pa
2.5 atm = 253,312.5 Pa — 253.313 kPa · 2.5331 bar · 36.74 psi. Working: 2.5 × 101,325 = 253,312.5.
2.5 atmospheres is 253,312.5 Pa — the pressure at about 15 m (50 ft) of sea-water depth (1 atm of air plus 1.5 atm of water), a typical hyperbaric-chamber treatment pressure, close to a car tyre (2.2–2.5 bar), and more than a domestic pressure cooker (about 1.7–2 atm absolute).
The other way: Pa to atm
| Pa | atm |
|---|---|
| 1 Pa | 0.00001 atm |
| 2 Pa | 0.00002 atm |
| 5 Pa | 0.000049 atm |
| 10 Pa | 0.000099 atm |
| 12 Pa | 0.000118 atm |
| 15 Pa | 0.000148 atm |
| 20 Pa | 0.000197 atm |
| 25 Pa | 0.000247 atm |
| 50 Pa | 0.000493 atm |
| 100 Pa | 0.000987 atm |
Common mistake
Mixing absolute and gauge pressure: a tyre gauge reading 2.5 bar is 2.5 bar above atmospheric — about 3.5 atm absolute.
Frequently asked questions
Is the conversion exact?
Yes — the factor follows from the legal definition of the units (1 atm = 101,325 Pa), so the only rounding is in the last decimal place shown.
How do I convert a different value?
Use the atm to Pa converter for any number, or the pressure conversion guide for every pressure unit and formula in one place.
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