PSI to ATM Converter
| psi | atm | The pressure |
|---|---|---|
| 14.7 | 1 | sea level |
| 32 | 2.18 | car tire (gauge) |
| 110 | 7.5 | road bike tire |
| 3000 | 204 | scuba tank |
An atmosphere is the pressure of the air on your shoulders at sea level - 14.696 pounds per square inch - and it is the unit science counts pressure in: chemistry's standard conditions, diving's depth math and thermodynamics' tables all speak atm. Type either number and the converter lands the other.
The number that startles everyone is the scuba tank: 3000 psi sounds enormous until the atmosphere scale puts it at about 204 - which is exactly the point, because a diver at 30 meters breathes at four atmospheres and needs to know it. The table runs the ladder from bicycle tire to tank, and the FAQs settle gauge versus absolute before it bites.
How to use
- Type the psi from a gauge or spec sheet - atmospheres appear instantly, or run the reverse from a chemistry problem.
- Read the table for the landmarks: car tire near 2 atm, scuba tank past 200, and every 10 meters of seawater adds one more.
- Chemistry values are absolute; dive gauges read relative - the FAQs explain the one-convention shift this converter's answers assume.
Frequently asked questions
How many psi is one atmosphere?
14.6959 - the weight of Earth's air column pressing on one square inch at sea level. The atm is defined as exactly 101,325 pascals, and 14.696 psi is that same pressure in the customary dialect. One bar, the near-twin divers and meteorologists use, is 14.504 psi - two percent shy of an atmosphere, a gap worth respecting on any dive computer.
Why is a 3000 psi scuba tank only 204 atm?
Because atmospheres are big: each one is the entire weight of the atmosphere overhead. Divide 3000 by 14.696 and the tank holds about 204 atmospheres of air - which sounds alarming until you remember the diver's body already lives under one, and the regulator's whole job is stepping that pressure down to exactly the surrounding water's, breath by breath.
What is the difference between psi gauge and psi absolute?
A gauge reads zero at sea level - it measures pressure above the atmosphere - while absolute counts the atmosphere in. A flat tire reads 0 psig but 14.7 psia: the atmosphere is still pressing on it. Chemistry's atm values are absolute; dive gauges, tire gauges and compressors read gauge. Mixing the two conventions shifts every answer by one atmosphere, which matters at laboratory pressures and barely at tank ones.
How does depth change atmospheres?
Every ten meters of seawater adds roughly one atmosphere - the weight of a water column that tall equals the whole air column's. At 30 meters a diver breathes four atm; at 40, five. That ladder is why depth is pressure in diving: partial pressures of oxygen become the safety variable, and the recreational limit of 40 meters is really a statement about five atmospheres.
What pressure is a car tire in atmospheres?
A typical car tire at 32 psi gauge is about 2.2 atmospheres above the surrounding air, or 3.2 absolute. Bicycle road tires run four to eight times that; the table lists the common points. The atm view makes the comparisons honest: a road bike tire at 110 psi carries about seven and a half atmospheres, which is why it hums on pavement and a car tire does not.