Convert Atmospheres to Bars
1 standard atmosphere is 1.01325 bar. One standard atmosphere is exactly 1.01325 bars.
One standard atmosphere is 1.01325 bars. To convert atmospheres to bars, multiply by 1.01325; to go the other way, divide by 1.01325 or multiply by 0.98692327. The factor is exact rather than rounded: it follows from NIST Special Publication 811.
Factor checked against the defining standard · How we check
- Atmospheres × 1.01325
value * 1.013251.013 bar
1 standard atmosphere in every pressure unit
| Unit | Value | Exact factor |
|---|---|---|
| pounds per square inch | 14.69594878 psi | × 14.6959487755 |
| bars | 1.01325 bar | × 1.01325 |
| pascals | 101,325 Pa | × 101,325 |
| kilopascals | 101.325 kPa | × 101.325 |
| megapascals | 0.101325 MPa | × 0.101325 |
| atmospheres (as entered) | 1 atm | — |
| torr | 760 Torr | × 760 |
| inches of mercury | 29.9212524 inHg | × 29.9212524019 |
Factors are entered by hand from NIST Special Publication 811 rather than derived from a units library, so the ones that terminate are exact rather than rounded.
How do you convert atmospheres to bars?
- 1.Take the measurement in atmospheres.
- 2.Multiply by 1.01325 — that is how many bars fit in one standard atmosphere.
- 3.To go back the other way, divide by 1.01325, or multiply by 0.98692327.
Worked example: 25 atmospheres to bars
- Formula
- atm × 1.01325 = bar
- Arithmetic
- 25 × 1.01325 = 25.33125 bar
- Answer
- 25 atm = 25.33125 bar
The factor is exact, so this figure is exact too — only the display is rounded.
Atmospheres to bars conversion table
| Atmospheres | Bars |
|---|---|
| 1 atm | 1.01325 bar |
| 2 atm | 2.0265 bar |
| 3 atm | 3.03975 bar |
| 4 atm | 4.053 bar |
| 5 atm | 5.06625 bar |
| 6 atm | 6.0795 bar |
| 7 atm | 7.09275 bar |
| 8 atm | 8.106 bar |
| 9 atm | 9.11925 bar |
| 10 atm | 10.1325 bar |
| 12 atm | 12.159 bar |
| 15 atm | 15.19875 bar |
| 20 atm | 20.265 bar |
| 25 atm | 25.33125 bar |
| 50 atm | 50.6625 bar |
| 100 atm | 101.325 bar |
| 200 atm | 202.65 bar |
| 300 atm | 303.975 bar |
| 500 atm | 506.625 bar |
| 1000 atm | 1,013.25 bar |
| 2000 atm | 2,026.5 bar |
| 5000 atm | 5,066.25 bar |
| 10000 atm | 10,132.5 bar |
What is a standard atmosphere?
Exactly 101,325 pascals by definition, not by measurement — it was fixed as a reference, and the real pressure outside your window is never precisely it.
What is a bar?
Exactly 100,000 pascals by definition, chosen because it sits within a per cent of atmospheric pressure at sea level. European tyre placards and dive computers use it.
How many bars are in a standard atmosphere?
One standard atmosphere is 1.01325 bars, exactly. Going the other way, one bar is 0.98692327 atmospheres. Both figures come from the same defined relation rather than from a measurement, which is why they are the same today as they were in 1959.
Every pressure unit here
| Unit | Symbol | One of these is |
|---|---|---|
| Pounds per square inch | psi | 6894.7573 pascal |
| Bars | bar | 100000 pascal |
| Pascals | Pa | the base unit |
| Kilopascals | kPa | 1000 pascal |
| Megapascals | MPa | 1000000 pascal |
| Atmospheres | atm | 101325 pascal |
| Torr | Torr | 133.32237 pascal |
| Inches of mercury | inHg | 3386.389 pascal |
Questions people actually ask
- How many bars are in a standard atmosphere?
- 1.01325. Exactly 100,000 pascals by definition, chosen because it sits within a per cent of atmospheric pressure at sea level. European tyre placards and dive computers use it.
- How do I convert bars back to atmospheres?
- Divide by 1.01325, or multiply by 0.98692327 — they are the same operation.
Other pressure conversions
Bars to atmospheres — the same conversion the other way.