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Convert Inches of mercury to Bars

1 inch of mercury is 0.033864 bar. One inch of mercury is exactly 0.03386389 bars.

One inch of mercury is 0.03386389 bars. To convert inches of mercury to bars, multiply by 0.03386389; to go the other way, divide by 0.03386389 or multiply by 29.52998. The factor is exact rather than rounded: it follows from NIST Special Publication 811. The pressure of a one-inch column of mercury at 0 °C, fixed by convention at 3,386.389 pascals.

Factor checked against the defining standard · How we check

Bars
0.033864 bar
Inches of mercury × 0.03386389
value * 0.033863890.034 bar

1 inch of mercury in every pressure unit

UnitValueExact factor
pounds per square inch0.4911541996 psi× 0.491154199634
bars0.03386389 bar× 0.03386389
pascals3,386.389 Pa× 3,386.389
kilopascals3.386389 kPa× 3.386389
megapascals0.003386389 MPa× 0.003386389
atmospheres0.03342106094 atm× 0.0334210609425
torr25.40000632 Torr× 25.4000063163
inches of mercury (as entered)1 inHg

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 inches of mercury to bars?

  1. 1.Take the measurement in inches of mercury.
  2. 2.Multiply by 0.03386389 — that is how many bars fit in one inch of mercury.
  3. 3.To go back the other way, divide by 0.03386389, or multiply by 29.52998.

Worked example: 25 inches of mercury to bars

Formula
inHg × 0.03386389 = bar
Arithmetic
25 × 0.03386389 = 0.846597 bar
Answer
25 inHg = 0.846597 bar

The factor is exact, so this figure is exact too — only the display is rounded.

Inches of mercury to bars conversion table

Inches of mercuryBars
1 inHg0.033864 bar
2 inHg0.067728 bar
3 inHg0.101592 bar
4 inHg0.135456 bar
5 inHg0.169319 bar
6 inHg0.203183 bar
7 inHg0.237047 bar
8 inHg0.270911 bar
9 inHg0.304775 bar
10 inHg0.338639 bar
12 inHg0.406367 bar
15 inHg0.507958 bar
20 inHg0.677278 bar
25 inHg0.846597 bar
50 inHg1.693195 bar
100 inHg3.386389 bar
200 inHg6.772778 bar
300 inHg10.159167 bar
500 inHg16.931945 bar
1000 inHg33.86389 bar
2000 inHg67.72778 bar
5000 inHg169.31945 bar
10000 inHg338.6389 bar

What is an inch of mercury?

The pressure of a one-inch column of mercury at 0 °C, fixed by convention at 3,386.389 pascals. US aviation altimeters and barometers read in 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 an inch of mercury?

One inch of mercury is 0.03386389 bars, exactly. Going the other way, one bar is 29.52998 inches of mercury. 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 bars are in an inch of mercury?
0.03386389. 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 inches of mercury?
Divide by 0.03386389, or multiply by 29.52998 — they are the same operation.

Other pressure conversions

Bars to inches of mercury — the same conversion the other way.