Atmospheres to Bar
Convert atmospheres (atm) to bar (bar). Both measure force per area, and the conversion comes up in weather, automotive, diving work.
The Formula
``
bar = atmospheres × 1.01325
atmospheres = bar × 0.986923266716
`
One atmosphere is 1.0132 bar, and one bar is 0.986923 atmospheres.
Conversion Table
| Atmospheres | Bar |
|---|---|
| 1 atm | 1.0132 bar |
| 2 atm | 2.0265 bar |
| 5 atm | 5.0663 bar |
| 10 atm | 10.1325 bar |
| 25 atm | 25.3313 bar |
| 50 atm | 50.6625 bar |
| 100 atm | 101.325 bar |
| 500 atm | 506.625 bar |
| 1,000 atm | 1,013.25 bar |
The Other Direction
| Bar | Atmospheres |
|---|---|
| 1 bar | 0.986923 atm |
| 2 bar | 1.9738 atm |
| 5 bar | 4.9346 atm |
| 10 bar | 9.8692 atm |
| 25 bar | 24.6731 atm |
| 50 bar | 49.3462 atm |
| 100 bar | 98.6923 atm |
| 500 bar | 493.4616 atm |
| 1,000 bar | 986.9233 atm |
What Each Unit Is
Atmospheres (atm) — exactly 101,325 pascals, by definition. The mean air pressure at sea level, adopted as a reference standard.
Bar (bar) — exactly 100,000 pascals — close to, but not exactly, one atmosphere. Introduced by meteorologist Vilhelm Bjerknes; weather maps use millibars.
A Sense of Scale
Pressure doubles at 10 m underwater- Everest’s summit is about 0.33 atm
- Sea-level pressure is about 1.013 bar
- Diving adds 1 bar per 10 m of depth
Doing It in Your Head
Multiply by 1. That is off by 1.31% — close enough to judge a
distance, a weight or a price, and not close enough to sign off on a drawing.
Exact Mental shortcut 10.1325 bar 10 bar 101.325 bar 100 bar
Precision
The factor 1.01325 is rounded. For engineering work carry more digits than the table above, and round only at the end — rounding at each step compounds.
In Code
`javascript
const atmosphereToBar = (value) => value * 1.01325;
``
Where This Conversion Comes Up
- Weather
- Automotive
- Diving
- Aviation
- HVAC
How Many Decimals Do You Need?
Rounding the factor costs accuracy, and how much depends on the factor. Converting 137 atm with the factor truncated at each decimal place:
| Decimals kept | Factor | 137 atm becomes | Error |
|---|---|---|---|
| 0 | 1 | 137 | 1.3077% |
| 1 | 1 | 137 | 1.3077% |
| 2 | 1.01 | 138.37 | 0.3208% |
| 3 | 1.013 | 138.781 | 0.0247% |
| 4 | 1.0132 | 138.808 | 0.0049% |
The right number of significant figures is set by your input, not by the converter. If you measured atmospheres to three significant figures, the answer in bar is only good to three — writing more digits claims precision the measurement never had.