Atmospheres to Bars
Type a value in either box to convert between atmospheres and bars. The factor is 1.01325.
| Atmospheres | Bars |
|---|---|
| 1 atm | 1.01325 bar |
| 2 atm | 2.0265 bar |
| 3 atm | 3.03975 bar |
| 5 atm | 5.06625 bar |
| 10 atm | 10.1325 bar |
| 25 atm | 25.33125 bar |
| 50 atm | 50.6625 bar |
| 100 atm | 101.325 bar |
How to use
- Enter a value in the Atmospheres field.
- The Bars figure appears immediately — no button to press.
- Typing in the Bars field converts back to Atmospheres the same way.
- Use the reference table for the values that come up most often.
Atmospheres to Bars formula
To convert atmospheres to bars, multiply by 1.01325.
bar = atm × 1.01325
Why this factor: the atmosphere and the bar are both defined against the pascal, so dividing one definition by the other gives 1.01325 directly. Both definitions are set out in full below.
To go the other way, divide by 1.01325 — or use the Bars to Atmospheres converter, which is the same calculation reversed.
Worked example
Start with 760 atm. Multiply by 1.01325 to get 770.07 bar.
760 atm × 1.01325 = 770.07 bar
The converter above does this for any value you type, in either direction.
What is an atmosphere?
A standard atmosphere is a fixed reference pressure, originally average sea-level air pressure.
Definition: Defined as exactly 101,325 pascals — an exact convention, not a measurement.
Where it is used: Chemistry reference conditions, diving pressure, and high-pressure physics.
What is a bar?
A bar is a metric pressure unit chosen to sit very close to atmospheric pressure.
Definition: Exactly 100,000 pascals by definition. Standard atmosphere is 1.01325 bar, so a bar is slightly less.
Where it is used: European tire and hydraulic pressures, diving depth equivalents, and espresso machine ratings.
Worth knowing: Close to one atmosphere but not equal to it — the difference is about 1.3%.
Atmospheres vs Bars
The atmosphere is a specialized unit while the bar is a metric unit. That is why the factor between them is not a round number: the two systems were defined independently and only later tied together by exact agreement.
Frequently asked questions
How many bars are in an atmosphere?
One atmosphere equals 1.01325 bars.
What is the formula to convert atmospheres to bars?
Multiply the number of atmospheres by 1.01325. To reverse it, divide by 1.01325 instead.
How do I convert bars back to atmospheres?
Divide by 1.01325, which is the same as multiplying by 0.986923267.
How many bars are in 10 atmospheres?
10 atm works out to 10.1325 bar.
Is there anything to watch out for with bars?
Close to one atmosphere but not equal to it — the difference is about 1.3%.
How is the atmosphere defined?
Defined as exactly 101,325 pascals — an exact convention, not a measurement.