Bar to Atmospheres Converter
Convert bar to standard atmospheres — one bar is 0.9869 atm, close to sea-level pressure but not equal to it. Results update as you type; exact factors shown.
One bar is 0.9869 standard atmospheres — see the exact factor, not a rounded rule of thumb.
How the bar to atmospheres 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 bar | 0.4935 atm | bars to standard atmospheres |
| 1 bar | 0.9869 atm | bar to standard atmospheres |
| 1.0133 bar | 1 atm | bars to standard atmospheres |
| 1.5 bar | 1.4804 atm | bars to standard atmospheres |
| 2 bar | 1.9738 atm | bars to standard atmospheres |
| 2.5 bar | 2.4673 atm | bars to standard atmospheres |
| 3 bar | 2.9608 atm | bars to standard atmospheres |
| 5 bar | 4.9346 atm | bars to standard atmospheres |
| 10 bar | 9.8692 atm | bars to standard atmospheres |
| 50 bar | 49.3462 atm | bars to standard atmospheres |
| 100 bar | 98.6923 atm | bars to standard atmospheres |
| 200 bar | 197.3847 atm | bars to standard atmospheres |
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
Is one bar the same as one atmosphere?
Almost, but not exactly — 1 bar is 0.98692 atm. A standard atmosphere is 1.01325 bar.
Why do the two units differ?
The atmosphere was defined from average sea-level pressure; the bar was defined as a round 100,000 pascals.
What is 2 bar in atm?
1.974 atm.
Which unit do scuba divers use?
Bar almost everywhere, because each 10 m of sea water adds very nearly 1 bar.
What is 200 bar in atm?
197.4 atm — a typical full scuba cylinder.
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.