Pressure
atmtombar
Convert standard atmospheres (atm) to millibars (mbar).
Factor1 atm = 1013.25 mbar
Converter
atm
Accepts numbers or expressions, e.g. 150 + 14.7
Result
mbar
Rendered to 6 significant figures.
Formula
Formula
mbar = atm × 1013.25
Multiply any value in standard atmospheres by 1013.25 to obtain the value in millibars.
Worked example
Convert 1 atm to mbar.
- 01Start with 1 atm.
- 02Multiply by the conversion factor: 1 × 1013.25 = 1013.25 mbar.
Result1 atm = 1013.25 mbar
Conversion table
| atm | mbar |
|---|---|
| 1 | 1013.3 |
| 2 | 2026.5 |
| 5 | 5066.3 |
| 10 | 10133 |
| 20 | 20265 |
| 50 | 50663 |
| 100 | 1.0133e+5 |
| 200 | 2.0265e+5 |
| 500 | 5.0663e+5 |
| 1000 | 1.0133e+6 |
Reference values rounded to 5 significant figures for display.
FAQ
What is the conversion factor from atm to mbar?
1 atm equals 1013.25 mbar. To convert, multiply the value in standard atmospheres by 1013.25.
How do I convert 1 atm to mbar?
1 atm = 1013.25 mbar. For any value, multiply by 1013.25.
How do I convert mbar back to atm?
Divide by the same factor — or equivalently, multiply by 0.0009869233. So 1 mbar = 0.000986923 atm.
When would I need to convert standard atmosphere to millibar?
Pressure conversions between atm and mbar are common when working with mixed-vendor instrumentation, when piping codes use different units to process datasheets, or when converting field readings into SI for hydraulic calculations.
Is the conversion exact?
The factor shown is precise to at least 7 significant figures. For most process-engineering work this is far better than instrument accuracy. For metrology or trade applications, refer to the relevant national standard (NIST, BIPM, ISO 80000).