How to Convert Atmospheres to PSI (atm to psi)
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 atmospheres into psi by hand, with examples and a quick-reference table.
The conversion
To convert atmospheres to psi, multiply the value by 14.6959494004. To go the other way, divide by the same number (or multiply by 0.068045961). For a quick estimate, multiply by about 15.
PSI = atmospheres × 14.6959494004
Worked examples
- 3 atm = 44.0878 psi
- 12.5 atm = 183.6994 psi
- 75 atm = 1,102.2 psi
Atmospheres to PSI table
| Atmospheres | PSI |
|---|---|
| 1 atm | 14.6959 psi |
| 2 atm | 29.3919 psi |
| 5 atm | 73.4797 psi |
| 10 atm | 146.9595 psi |
| 20 atm | 293.919 psi |
| 25 atm | 367.3987 psi |
| 50 atm | 734.7975 psi |
| 100 atm | 1,469.59 psi |
| 250 atm | 3,673.99 psi |
| 500 atm | 7,347.97 psi |
| 1,000 atm | 14,695.95 psi |
Common questions
Is atm to psi 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 PSI to Atmospheres 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.
Multiplying when you should divide
Converting to a smaller unit gives a bigger number, and converting to a larger unit gives a smaller one. If your answer moves the wrong way, you have inverted the factor.
Background
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.
Writing the units next to every number while you work is the simplest way to avoid mistakes. If the units do not cancel to leave the one you want, the calculation is set up wrongly.
For any value, use the Atmospheres to PSI Converter or browse all pressure converters.
Run your own numbers: Atmospheres to PSI Converter