Atmosphere to Bar Formula
bar = atm x 1.01325
Conversion factors follow SI relationships published by BIPM and NIST, where those standards apply.
Atmosphere to Bar Converter
Quick Answer
1 atm = 1.01325 bar
Formula: Bar = Atmosphere x 1.01325
Quick values
Worked examples
Convert 1 atm to bar
bar = 1 x 1.01325
Result: 1 atm = 1.01325 bar
Convert 10 atm to bar
bar = 10 x 1.01325
Result: 10 atm = 10.1325 bar
Convert 100 atm to bar
bar = 100 x 1.01325
Result: 100 atm = 101.325 bar
About Atmosphere and Bar
1 standard atmosphere is 101,325 Pa and 1 bar is 100,000 Pa, so 1 atm = 1.01325 bar exactly. Chemistry “1 atm” and European “1 bar” are close but not interchangeable for precision work.
Category hub: Pressure Conversion · Conversion charts · Conversion formulas
Atmosphere to Bar Conversion Table
| Atmosphere (atm) | Bar (bar) |
|---|---|
| 0.5 atm | 0.506625 bar |
| 1 atm | 1.01325 bar |
| 1.01325 atm | 1.02668 bar |
| 2 atm | 2.0265 bar |
| 5 atm | 5.06625 bar |
| 10 atm | 10.1325 bar |
| 20 atm | 20.265 bar |
| 50 atm | 50.6625 bar |
Browse all conversion charts → · Browse conversion formulas →
Practical use cases for Atmosphere to Bar
Tire and Vehicle Service
Passenger-car tire placards in the US are often in PSI, while many gauges and shop manuals list kPa or bar. Converting before inflation avoids under- or over-pressurizing a tire.
HVAC and Hydronics
Boiler, chiller, and duct-pressure specs mix PSI, kPa, and inches of water. Field techs convert so setpoints match the equipment nameplate.
Process and Plant Engineering
P&IDs and relief-valve datasheets may use PSI, bar, or kPa depending on the region. Accurate conversion is required before sizing piping and safety devices.
Meteorology and Aviation
Altimeter and station-pressure reports use inHg, hPa, or kPa. Pilots and weather desks convert between those scales for briefings and QNH settings.
Medical and Laboratory Gases
Cylinder pressures and ventilator settings are published in different units by manufacturer and country. Clinicians convert to the unit on the local gauge.
Hydraulics and Pneumatics
Pump and compressor curves are often published in bar or kPa while US shop drawings stay in PSI. Converting keeps actuator force and regulator settings consistent.
Atmosphere to Bar FAQs
Common questions about converting atmosphere to bar.
How do you convert atmospheres to bar?
Multiply atmospheres by 1.01325. Example: 1 atm = 1.01325 bar, 2 atm = 2.0265 bar, 10 atm = 10.1325 bar.
Why is 1 atm not equal to 1 bar?
The atmosphere was fixed from historical mercury-barometer work at 101,325 Pa. The bar was later defined as a round 100 kPa for metric engineering. The gap is 1.325%.
Can I treat 1 atm as 1 bar in a lab report?
Only if the method allows ~1% error. Gas-law homework often does. Relief-valve setpoints, custody transfer, and published vapor pressures should keep 1.01325.
Where does the atmospheres to bar factor come from?
Both constants are published in NIST SP 811 and the SI Brochure. This calculator applies 101,325 / 100,000 with no weather correction.
Charts and printable PDF
Use the matching atmosphere / bar chart when you need a printable table or offline reference.
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