Atmospheres to Bar Converter
Convert standard atmospheres to bar — one atmosphere is exactly 1.01325 bar. Results update as you type; exact factors shown.
One standard atmosphere is 1.0133 bars — see the exact factor, not a rounded rule of thumb.
How the atmospheres to bar converter works
Pressures convert through the pascal (1 N/m²). One bar is exactly 100 kPa; a standard atmosphere is exactly 101.325 kPa; 1 psi is 6.894757 kPa (a pound-force on a square inch); 1 mmHg is 133.322 Pa by the conventional definition.
The UK is metric for most trade and science but keeps miles, pints, stone and mpg (with the imperial gallon) in daily life.
Common pressure conversions
| From | To | Units |
|---|---|---|
| 0.5 atm | 0.5066 bar | standard atmospheres to bars |
| 1 atm | 1.0133 bar | standard atmosphere to bars |
| 1.5 atm | 1.5199 bar | standard atmospheres to bars |
| 2 atm | 2.0265 bar | standard atmospheres to bars |
| 3 atm | 3.0398 bar | standard atmospheres to bars |
| 5 atm | 5.0663 bar | standard atmospheres to bars |
| 10 atm | 10.1325 bar | standard atmospheres to bars |
| 20 atm | 20.265 bar | standard atmospheres to bars |
| 50 atm | 50.6625 bar | standard atmospheres to bars |
| 100 atm | 101.325 bar | standard atmospheres to bars |
| 150 atm | 151.9875 bar | standard atmospheres to bars |
| 200 atm | 202.65 bar | standard atmospheres to bars |
Units in this converter and their exact factors
| Unit | Symbol | One unit in pascals |
|---|---|---|
| pascal | Pa | 1 pascal |
| kilopascal | kPa | 1,000 pascal |
| megapascal | MPa | 1,000,000 pascal |
| bar | bar | 100,000 pascal |
| millibar (hectopascal) | mbar | 100 pascal |
| standard atmosphere | atm | 101,325 pascal |
| pound per square inch | psi | 6,894.757293168 pascal |
| millimetre of mercury | mmHg | 133.322387415 pascal |
| inch of mercury | inHg | 3,386.389 pascal |
FAQFrequently asked questions about pressure conversion
How many bar in one atmosphere?
Exactly 1.01325 bar, by definition.
Why is the atmosphere not a round number of bar?
Because the two were defined independently — the atmosphere from measured sea-level pressure, the bar as 100 kPa exactly.
What is 10 atm in bar?
10.1325 bar.
Which is used in science?
The pascal and its multiples; the atmosphere survives mainly in chemistry and the bar in engineering and diving.
Is 1 atm the pressure at sea level?
It is the standard reference for it. Real sea-level pressure varies roughly 0.95 to 1.05 atm with the weather.
Where these figures come from
- BIPM — The International System of Units (SI Brochure, 9th edition) — definitions of the base and derived units.
- NIST Special Publication 811 — Guide for the Use of the International System of Units — the exact conversion factors used here.
- National Physical Laboratory (NPL) — United Kingdom's national measurement authority.
Last checked: September 2026. Conversion factors are fixed by definition and do not change with tax years or regulations.