How to Convert PSI to Atmospheres (psi to atm)
Pressure conversions are used for tyre pressure (psi or bar), blood pressure readings in mmHg and weather maps in millibars. This guide shows how to convert psi into atmospheres by hand, with examples and a quick-reference table.
The conversion
To convert psi to atmospheres, multiply the value by 0.068045961. To go the other way, divide by the same number (or multiply by 14.6959494004). For a quick estimate, multiply by about 0.068.
Atmospheres = psi × 0.068045961
Worked examples
- 3 psi = 0.204138 atm
- 12.5 psi = 0.850575 atm
- 75 psi = 5.1034 atm
PSI to Atmospheres table
| PSI | Atmospheres |
|---|---|
| 1 psi | 0.068046 atm |
| 2 psi | 0.136092 atm |
| 5 psi | 0.34023 atm |
| 10 psi | 0.68046 atm |
| 20 psi | 1.3609 atm |
| 25 psi | 1.7011 atm |
| 50 psi | 3.4023 atm |
| 100 psi | 6.8046 atm |
| 250 psi | 17.0115 atm |
| 500 psi | 34.023 atm |
| 1,000 psi | 68.046 atm |
Common questions
Is psi to atm exact?
The factors used here are the internationally defined values where they exist; results are rounded for display only.
How do I convert back?
Use the Atmospheres to PSI converter.
Mistakes to avoid
Rounding the factor too early
Using 3 instead of 3.28 for feet per metre introduces an error of almost 9% before you have started.
Forgetting squared and cubed units
Area and volume factors are the length factor squared or cubed, so 1 m² is about 10.76 sq ft, not 3.28.
Mixing similar-sounding units
US and imperial gallons, pints and tons are different sizes, and decimal kilobytes differ from binary kibibytes.
Background
For everyday use, three or four significant figures are usually enough. Engineering, science and trade documents may need more, and rounding should happen only at the end of a calculation.
Many conversion factors are exact by definition. The inch has been defined as exactly 2.54 centimetres since 1959, and the pound as exactly 0.45359237 kilograms, so conversions involving them can be as precise as you need.
A conversion table is handy for common values, but a calculator is faster and avoids interpolation errors for anything in between.
For any value, use the PSI to Atmospheres Converter or browse all pressure converters.
Run your own numbers: PSI to Atmospheres Converter