Bar to Atmospheres Converter
Unit ConversionConvert bar to standard atmospheres. 1 bar is about 0.986923 standard atmospheres, with a conversion table and the reverse conversion.
Atmospheres
Equivalent pressure in standard atmospheres
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SponsoredThis converter turns bar into standard atmospheres (bar to atm). Enter a value and the result updates as you type. 1 bar is about 0.986923 standard atmospheres.
1 bar is exactly 100,000 pascals, a metric unit that is not part of the SI. 1 standard atmosphere is exactly 101,325 pascals, a reference value close to average sea-level air pressure. The two are close, which is why they are easy to mix up: a bar is about 1.3% smaller than an atmosphere.
The result shows 0 for a negative entry, because absolute pressure, counted from a perfect vacuum, cannot be negative. The result is rounded to 6 decimal places.
How to Convert Bar to Atmospheres
To convert bar to standard atmospheres, multiply by 100,000 and divide by 101,325. For example, 2 bar is about 1.973847 atm.
To go from standard atmospheres back to bar, multiply atmospheres by 1.01325.
Bar to Atmospheres Conversion Table
Common bar values converted to standard atmospheres, rounded to 6 decimal places.
| Bar | Atmospheres |
|---|---|
| 0.5 bar | 0.493462 atm |
| 1 bar | 0.986923 atm |
| 1.01325 bar | 1 atm |
| 2 bar | 1.973847 atm |
| 3 bar | 2.96077 atm |
| 5 bar | 4.934616 atm |
| 10 bar | 9.869233 atm |
| 20 bar | 19.738465 atm |
| 50 bar | 49.346163 atm |
| 100 bar | 98.692327 atm |
Why 1 Bar Is Less Than 1 Atmosphere
The bar was chosen as a round metric number, 100,000 Pa, while the atmosphere was fixed at 101,325 Pa to match sea-level air pressure. So 1 bar is about 0.986923 atm, and 1 atm = 1.01325 bar. The standard atmosphere is also called the physical atmosphere, which sets it apart from the technical atmosphere (at): one kilogram-force per square centimeter, about 0.967841 atm.
The difference matters in chemistry. The IUPAC Green Book notes that a standard pressure of 1 bar has been recommended since 1982, while older texts use 1 atm, so gas volumes at standard conditions differ slightly between sources. The Ideal Gas Law Calculator takes pressure in atmospheres, and real air pressure falls with altitude, which the Oxygen Saturation Altitude Estimator relates to blood oxygen.
Frequently Asked Questions
What is 5 bar in atm?
5 bar is about 4.934616 atm.
How many bar is 1 atm?
1 atm is exactly 1.01325 bar.
Is bar or atm bigger?
The atmosphere is bigger. 1 atm is 101,325 Pa and 1 bar is 100,000 Pa.
Is the Bar to Atmospheres factor exact?
The reverse direction is exact: 1 standard atmosphere equals exactly 1.01325 bar. In this direction the factor has no finite decimal form, so 1 bar is about 0.986923 standard atmospheres. The calculator uses the full value and rounds only the result it shows.
What happens if I enter a negative value?
It shows 0. Both values are treated as absolute pressures, which cannot be negative. For gauge readings below the surrounding air, see the gauge converters listed below.
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