Convert Bar to Atmospheres
Bar to atmospheres is the conversion you need when a pressure is in bar but you want it in standard atmospheres — the unit tied to sea-level air pressure. One bar is approximately 0.98692327 atm, just under one atmosphere, because the two units are close but not the same.
Bar to Atmospheres conversion table
| Bar (bar) | Atmospheres (atm) |
|---|---|
| 1 | 0.986923 |
| 2 | 1.973847 |
| 3 | 2.96077 |
| 5 | 4.934616 |
| 10 | 9.869233 |
| 20 | 19.738465 |
| 50 | 49.346163 |
| 100 | 98.692327 |
| 500 | 493.461633 |
| 1,000 | 986.923267 |
The formula
To convert bar to atmospheres, multiply the number of bar by 0.98692327:
atmospheres = bar × 0.98692327
A worked example
Say you have a reading of 1 bar and want it in atmospheres:
1 × 0.98692327 = 0.98692327 atm
So 1 bar is just under one atmosphere.
Why it's an approximation
The bar and the standard atmosphere were defined separately, so they don't match exactly. One atmosphere is set at 1.01325 bar, which makes one bar approximately 0.9869232667160128 atm — a value that runs on without terminating cleanly. Any short version like 0.98692327 is rounded, which is why this conversion stays approximate even though the two units sit very close together.
When you'll use it
Comparing a weather or diving pressure given in bar against the standard atmosphere, or reading a scientific figure that quotes atmospheres when your source is in bar.
Frequently asked questions
How many atmospheres are in one bar?
About 0.98692327 atm — just under one atmosphere. The bar and the atmosphere are close but not identical, so this factor is rounded.
Is one bar the same as one atmosphere?
Almost, but not quite. One bar is approximately 0.98692327 atm, and one atmosphere is 1.01325 bar. They're close enough to swap in casual talk, but not equal.
Is the bar to atmospheres conversion exact?
No. One standard atmosphere is defined as 1.01325 bar, so a bar works out to approximately 0.98692327 atm — a rounded figure, not an exact one.