Authoritative definitions of the International System of Units and SI prefixes.
Dedicated unit pair
Bar to Atmospheres
Convert bar to atm instantly, then review the formula, assumptions, and rounding guidance.
Pressure & stressInstant result
Decimals
Formula result = input × 100000 ÷ 101325. 1 bar = 0.9869 atm
Common examples
One value, several units
Pascals100,000 Pa
Kilopascals100 kPa
Megapascals0.1 MPa
Atmospheres0.9869 atm
Pounds per square inch14.5038 psi
Millimetres of mercury750.0616 mmHg
Conversion table
| bar | atm |
|---|---|
| 1 bar | 0.9869 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 |
Conversion chart
1 bar0.9869 atm
5 bar4.9346 atm
10 bar9.8692 atm
25 bar24.6731 atm
50 bar49.3462 atm
Worked example
Standard atmosphere is 101,325 pascals.
Unit definition
Bar (bar) One bar equals 100,000 pascal.
Unit history
Bar is represented here using its modern SI definition or an internationally accepted relationship to an SI base unit.
Step by step
1. Parse the value, including fractions.
2. Convert bar to pascal.
3. Convert the base value to atm and apply your display precision.
Understand the result before using it
Bar to Atmospheres converts a value measured in Bar (bar) into the equivalent value in Atmospheres (atm). The numerical value changes because the size and definition of the selected unit changes; the underlying quantity does not.
Calculated result
The conversion follows the displayed unit relationship. Display rounding can hide additional digits, and measured inputs cannot become more accurate merely by changing units.
Formula, assumptions, and example
Formula
result = input × 100000 ÷ 101325
Assumptions
- Bar and Atmospheres represent the same pressure & stress quantity.
- The input is expressed in bar; the output is expressed in atm.
- The unit definitions and conventional relationship shown on this page apply.
Worked example
1 bar = 0.986923266716 atm. For another value, apply the same relationship and round only to the precision your source measurement supports.
When to use it
Good uses
- Read a bar measurement in a document that expects atm.
- Compare a bar value with a value reported in atmospheres.
- Check the bar-to-atm arithmetic before copying the result into another calculation.
Limitations
Common mistakes to avoid
- Do not confuse bar with another unit that has a similar name or symbol.
- Round the output to a precision justified by the original measurement.
- Verify safety-critical, regulated, laboratory, and contractual conversions against the controlling standard.
Sources and further reading
These references explain the underlying standards or provide authoritative context. Your own contract, institution, clinician, product documentation, local code, or governing standard may be the controlling source.
Guidance on unit names, symbols, conversions, and numerical presentation.
Questions about this calculation
How do I convert Bar to Atmospheres?
result = input × 100000 ÷ 101325 Using the displayed relationship, 1 bar equals 0.986923266716 atm.
How many Atmospheres are in one Bar?
One Bar is 0.986923266716 Atmospheres. The displayed digits may be rounded.
Can I reverse the bar to atm conversion?
Yes. Swap the source and target units in the converter. The reverse relationship converts atm back to bar.
Is the Bar to Atmospheres result exact?
The conversion follows the displayed unit relationship. Display rounding can hide additional digits, and measured inputs cannot become more accurate merely by changing units.