How to Convert Atmospheres to Bar (atm to bar)
Pressure conversions are used for tyre pressure (psi or bar), blood pressure readings in mmHg and weather maps in millibars. This guide shows how to convert atmospheres into bar by hand, with examples and a quick-reference table.
The conversion
To convert atmospheres to bar, multiply the value by 1.01325. To go the other way, divide by the same number (or multiply by 0.9869232667). For a quick estimate, multiply by about 1.
Bar = atmospheres × 1.01325
Worked examples
- 3 atm = 3.0397 bar
- 12.5 atm = 12.6656 bar
- 75 atm = 75.9938 bar
Atmospheres to Bar table
| Atmospheres | Bar |
|---|---|
| 1 atm | 1.0132 bar |
| 2 atm | 2.0265 bar |
| 5 atm | 5.0663 bar |
| 10 atm | 10.1325 bar |
| 20 atm | 20.265 bar |
| 25 atm | 25.3313 bar |
| 50 atm | 50.6625 bar |
| 100 atm | 101.325 bar |
| 250 atm | 253.3125 bar |
| 500 atm | 506.625 bar |
| 1,000 atm | 1,013.25 bar |
Common questions
Is atm to bar exact?
The factors used here are the internationally defined values where they exist; results are rounded for display only.
How do I convert back?
Use the Bar to Atmospheres converter.
Mistakes to avoid
Mixing similar-sounding units
US and imperial gallons, pints and tons are different sizes, and decimal kilobytes differ from binary kibibytes.
Forgetting squared and cubed units
Area and volume factors are the length factor squared or cubed, so 1 m² is about 10.76 sq ft, not 3.28.
Multiplying when you should divide
Converting to a smaller unit gives a bigger number, and converting to a larger unit gives a smaller one. If your answer moves the wrong way, you have inverted the factor.
Background
Unit conversion is simply multiplication by a fixed ratio. The ratio between two units of the same quantity never changes, so once you know it you can convert any value in either direction.
Many conversion factors are exact by definition. The inch has been defined as exactly 2.54 centimetres since 1959, and the pound as exactly 0.45359237 kilograms, so conversions involving them can be as precise as you need.
For everyday use, three or four significant figures are usually enough. Engineering, science and trade documents may need more, and rounding should happen only at the end of a calculation.
For any value, use the Atmospheres to Bar Converter or browse all pressure converters.
Run your own numbers: Atmospheres to Bar Converter