Convert Atmospheres to Bar
1 atmosphere (atm) equals 1.01325 bar.
1 atm = 1.01325 bar
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk atmosphere to bar converter to paste a column from Excel.
How to Convert Atmosphere to Bar
- 1 atm = 1.01325 bar
- 1 bar = 0.9869232667 atm
- Example: convert 15 atm to bar: 15 atm = 15 × 1.01325 bar = 15.19875 bar
Formula
bar = atm × 1.01325
Derivation from SI units:
- 1 atm = 101 325 Pa (exact, by definition)
- 1 bar = 10⁵ Pa (exact, by definition)
- 1 atm = 101325 Pa ÷ 100000 Pa per bar = 1.01325 bar
Both units are defined exactly, so the factor is exact. Atmosphere definition: atmosphere; Bar definition: bar.
Worked examples
- 1 atm equals 1.01325 bar.
1 atm × 1.01325 = 1.01325 bar - At about 20 m depth the absolute pressure of 3 atm is 3.03975 bar.
3 atm × 1.01325 = 3.03975 bar
Atmosphere to Bar conversion table
| Atmospheres (atm) | Bar |
|---|---|
| 0.001 atm | 0.00101325 bar |
| 0.01 atm | 0.0101325 bar |
| 0.1 atm | 0.101325 bar |
| 0.25 atm | 0.2533125 bar |
| 0.5 atm | 0.506625 bar |
| 1 atm | 1.01325 bar |
| 1.5 atm | 1.519875 bar |
| 2 atm | 2.0265 bar |
| 2.5 atm | 2.533125 bar |
| 3 atm | 3.03975 bar |
| 4 atm | 4.053 bar |
| 5 atm | 5.06625 bar |
| 10 atm | 10.1325 bar |
| 20 atm | 20.265 bar |
| 50 atm | 50.6625 bar |
| 100 atm | 101.325 bar |
| 200 atm | 202.65 bar |
| 300 atm | 303.975 bar |
| 1000 atm | 1013.25 bar |
Where it's used
Converting atm to bar is common when gas-law results meet equipment and regulators rated in bar.
Atmosphere to other pressure units
| Conversion | 1 atm equals |
|---|---|
| atmosphere to pascal | 101325 Pa |
| atmosphere to kilopascal | 101.325 kPa |
| atmosphere to megapascal | 0.101325 MPa |
| atmosphere to psi | 14.69594878 psi |
| atmosphere to bar | 1.01325 bar |
| atmosphere to millibar | 1013.25 mbar |
| atmosphere to decibar | 10.1325 dbar |
| atmosphere to torr | 760 Torr |
| atmosphere to millimeter of mercury | 759.9998917 mmHg |
| atmosphere to millimeter of water | 10332.27453 mmH₂O |
| atmosphere to centimeter of water | 1033.227453 cmH₂O |
| atmosphere to inch of water | 406.7824617 inH₂O |
| atmosphere to inch of water (60 °F) | 407.1893586 inH₂O (60 °F) |
| atmosphere to inch of mercury | 29.92125558 inHg |
| atmosphere to barye | 1013250 Ba |
Frequently asked questions
Which is bigger, 1 bar or 1 atm?
1 atm is slightly bigger: 1 atm = 1.01325 bar.
How many bar are in 1 atmosphere?
1 atm = 1.01325 bar.
How do I convert atmospheres to bar?
Multiply the value in atm by 1.01325. For example, 15 atm × 1.01325 = 15.19875 bar.
Is the atm to bar conversion exact?
Yes. Both units are defined exactly, and 1 atm is exactly 1.01325 bar.
Sources
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "atmosphere, standard (atm)".
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "bar".
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Convert Atmospheres to Bar. Retrieved October 17, 2026, from https://scientificconverters.com/pressure/atmosphere-to-bar/
IEEE
Scientific Converters, "Convert Atmospheres to Bar," scientificconverters.com. Accessed: Oct. 17, 2026. [Online]. Available: https://scientificconverters.com/pressure/atmosphere-to-bar/