inHg to atm Converter

How to convert inches of mercury to atmospheres

Formulaatm = inHg × 0.03342105739

Multiply the value in inches of mercury by 0.03342105739. To go the other way, multiply by 29.92125558 (or divide by 0.03342105739).

An inch of mercury is smaller than a standard atmosphere: it takes 29.92125558 inches of mercury to make one standard atmosphere.

Worked examples

1 inch of mercury1 inHg × 0.03342105739 = 0.03342105739 atm
5 inches of mercury5 inHg × 0.03342105739 = 0.167105287 atm
10 inches of mercury10 inHg × 0.03342105739 = 0.3342105739 atm
20 inches of mercury20 inHg × 0.03342105739 = 0.6684211479 atm
100 inches of mercury100 inHg × 0.03342105739 = 3.342105739 atm

Inches of mercury to atmospheres conversion table

Values are calculated by the conversion engine and rounded to 8 significant figures.

Inches of mercury to atmospheres: 0.1–10 inHg
Inches of mercury (inHg)	Atmospheres (atm)
0.1 inHg	0.0033421057 atm
0.25 inHg	0.0083552643 atm
0.5 inHg	0.016710529 atm
1 inHg	0.033421057 atm
2 inHg	0.066842115 atm
3 inHg	0.10026317 atm
4 inHg	0.13368423 atm
5 inHg	0.16710529 atm
6 inHg	0.20052634 atm
7 inHg	0.2339474 atm
8 inHg	0.26736846 atm
9 inHg	0.30078952 atm
10 inHg	0.33421057 atm

Inches of mercury to atmospheres: 12–1,000 inHg
Inches of mercury (inHg)	Atmospheres (atm)
12 inHg	0.40105269 atm
15 inHg	0.50131586 atm
20 inHg	0.66842115 atm
25 inHg	0.83552643 atm
30 inHg	1.0026317 atm
40 inHg	1.3368423 atm
50 inHg	1.6710529 atm
75 inHg	2.5065793 atm
100 inHg	3.3421057 atm
250 inHg	8.3552643 atm
500 inHg	16.710529 atm
1,000 inHg	33.421057 atm

About the units

Inch of mercury (inHg)

About 3,386.39 Pa. US weather reports and aircraft altimeters use inches of mercury (standard is 29.92 inHg). One inch of mercury equals 3,386.38864 pascals (Pa).

Standard atmosphere (atm)

Exactly 101,325 Pa — average sea-level air pressure.

Frequently asked questions

How many atmospheres are in one inch of mercury?

There are 0.03342105739 atmospheres in one inch of mercury, and this value is exact by definition.

How do I convert inches of mercury to atmospheres?

Multiply the number of inches of mercury by 0.03342105739. For example, 10 inHg × 0.03342105739 = 0.3342105739 atm.

How many inches of mercury are in one standard atmosphere?

One standard atmosphere equals 29.92125558 inches of mercury. That is the reverse factor, 1 ÷ 0.03342105739.

What is 10 inches of mercury in atmospheres?

10 inHg = 0.3342105739 atm.

Is this inHg to atm converter accurate?

Yes. Both units are defined exactly in terms of SI units, so the conversion factor is exact; results are shown to 12 significant figures by default and you can change precision in the converter. Calculations run in your browser using the same tested engine that generated this page.