Bar to Atmospheres
Convert bar (bar) to atmospheres (atm). Both measure force per area, and the conversion comes up in weather, automotive, diving work.
The Formula
``
atmospheres = bar × 0.986923266716
bar = atmospheres × 1.01325
`
One bar is 0.986923 atmospheres, and one atmosphere is 1.0132 bar.
Conversion Table
| 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 |
The Other Direction
| 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 |
What Each Unit Is
Bar (bar) — exactly 100,000 pascals — close to, but not exactly, one atmosphere. Introduced by meteorologist Vilhelm Bjerknes; weather maps use millibars.
Atmospheres (atm) — exactly 101,325 pascals, by definition. The mean air pressure at sea level, adopted as a reference standard.
A Sense of Scale
Sea-level pressure is about 1.013 bar- Diving adds 1 bar per 10 m of depth
- Pressure doubles at 10 m underwater
- Everest’s summit is about 0.33 atm
Doing It in Your Head
Multiply by 1. That is off by 1.33% — close enough to judge a
distance, a weight or a price, and not close enough to sign off on a drawing.
Exact Mental shortcut 9.8692 atm 10 atm 98.6923 atm 100 atm
Precision
The factor 0.986923266716 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 barToAtmosphere = (value) => value * 0.986923266716;
``
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 bar with the factor truncated at each decimal place:
| Decimals kept | Factor | 137 bar becomes | Error |
|---|---|---|---|
| 0 | 1 | 137 | 1.3250% |
| 1 | 1 | 137 | 1.3250% |
| 2 | 0.99 | 135.63 | 0.3118% |
| 3 | 0.987 | 135.219 | 0.0078% |
| 4 | 0.9869 | 135.205 | 0.0024% |
The right number of significant figures is set by your input, not by the converter. If you measured bar to three significant figures, the answer in atmospheres is only good to three — writing more digits claims precision the measurement never had.