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Convert Bars to Atmospheres

1 bar is 0.986923 atm. One bar is exactly 0.986923266716 atmospheres.

One bar is 0.98692327 atmospheres. To convert bars to atmospheres, multiply by 0.98692327; to go the other way, divide by 0.98692327 or multiply by 1.01325. The factor is exact rather than rounded: it follows from NIST Special Publication 811. Exactly 100,000 pascals by definition, chosen because it sits within a per cent of atmospheric pressure at sea level.

Factor checked against the defining standard · How we check

Atmospheres
0.986923 atm
Bars × 0.98692327
value * 0.9869232667160.987 atm

1 bar in every pressure unit

UnitValueExact factor
pounds per square inch14.50377377 psi× 14.503773773
bars (as entered)1 bar
pascals100,000 Pa× 100,000
kilopascals100 kPa× 100
megapascals0.1 MPa× 0.1
atmospheres0.9869232667 atm× 0.986923266716
torr750.0616827 Torr× 750.061682704
inches of mercury29.52998016 inHg× 29.5299801647

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 bars to atmospheres?

  1. 1.Take the measurement in bars.
  2. 2.Multiply by 0.98692327 — that is how many atmospheres fit in one bar.
  3. 3.To go back the other way, divide by 0.98692327, or multiply by 1.01325.

Worked example: 25 bars to atmospheres

Formula
bar × 0.98692327 = atm
Arithmetic
25 × 0.98692327 = 24.673082 atm
Answer
25 bar = 24.673082 atm

The factor is rounded for display; the figure above is computed from the full value.

Bars to atmospheres conversion table

BarsAtmospheres
1 bar0.986923 atm
2 bar1.973847 atm
3 bar2.96077 atm
4 bar3.947693 atm
5 bar4.934616 atm
6 bar5.92154 atm
7 bar6.908463 atm
8 bar7.895386 atm
9 bar8.882309 atm
10 bar9.869233 atm
12 bar11.843079 atm
15 bar14.803849 atm
20 bar19.738465 atm
25 bar24.673082 atm
50 bar49.346163 atm
100 bar98.692327 atm
200 bar197.384653 atm
300 bar296.07698 atm
500 bar493.461633 atm
1000 bar986.923267 atm
2000 bar1,973.846533 atm
5000 bar4,934.616334 atm
10000 bar9,869.232667 atm

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.

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.

How many atmospheres are in a bar?

One bar is 0.98692327 atmospheres. Going the other way, one standard atmosphere is 1.01325 bars. 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

UnitSymbolOne of these is
Pounds per square inchpsi6894.7573 pascal
Barsbar100000 pascal
PascalsPathe base unit
KilopascalskPa1000 pascal
MegapascalsMPa1000000 pascal
Atmospheresatm101325 pascal
TorrTorr133.32237 pascal
Inches of mercuryinHg3386.389 pascal

Source: NIST Special Publication 811 — pound-force is exactly 4.4482216152605 N and the inch exactly 0.0254 m

Questions people actually ask

How many atmospheres are in a bar?
0.98692327. 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.
How do I convert atmospheres back to bars?
Divide by 0.98692327, or multiply by 1.01325 — they are the same operation.

Other pressure conversions

Atmospheres to bars — the same conversion the other way.