PSI to Atmospheres (psi to atm)
One standard atmosphere is defined as exactly 101,325 Pa and one psi is 6,894.757 Pa (NIST SP 811), so 1 atm = 14.695949 psi. To convert psi to atm, divide by 14.696 — 100 psi is 6.80 atm.
Formula
atm = psi ÷ 14.695949 (= psi × 0.0680460)
Example: 14.696 psi = 1 atmospheres.
PSI to Atmospheres chart
| psi | atmospheres |
|---|---|
| 1 | 0.068046 |
| 5 | 0.34023 |
| 10 | 0.68046 |
| 14.696 | 1 |
| 20 | 1.36092 |
| 30 | 2.04138 |
| 32 | 2.17747 |
| 35 | 2.38161 |
| 50 | 3.4023 |
| 100 | 6.8046 |
| 150 | 10.2069 |
| 200 | 13.6092 |
| 500 | 34.023 |
| 1,000 | 68.046 |
| 3,000 | 204.138 |
Good to know
Gauge or absolute? An atmosphere is an absolute unit — it counts from a perfect vacuum — while most gauges read psig, the pressure above the surrounding air. A tire at 32 psig is really at about 46.7 psia, which is 3.18 atm absolute, not 2.18. Add 14.696 psi before dividing if you need absolute atmospheres; chemistry and gas-law problems almost always do.
Scuba and compressed gas: an aluminum 80 cylinder filled to 3,000 psi holds gas at about 204 atm (gauge), which is why divers think in bar or atmospheres — every 33 feet (10 m) of seawater adds roughly one more atmosphere of pressure on the diver.
For bar, 1 atm = 1.01325 bar, so atmospheres and bar differ by only about 1.3%. Use bar for tires and espresso machines, atm for lab and textbook work.
Frequently asked questions
How many atm is 1 psi?
1 psi is 0.068046 atm.
How many psi is 1 atm?
1 standard atmosphere is 14.695949 psi — usually rounded to 14.7 psi.
What is 100 psi in atm?
100 psi is 6.805 atm.
Is atm gauge or absolute pressure?
Absolute. 1 atm is the pressure of the air at sea level measured from a vacuum. A gauge reading in psig must have 14.696 psi added before converting if you want absolute atmospheres.