Convert inches of mercury to atmospheres

1 inHg=0.03342atm

Use the converter below to change any inches of mercury value into atmospheres instantly — with formula, conversion table, and real-world examples.

You have

Equals

0.033421

Conversion formula

Forward

atmospheres = inches of mercury × 0.03342

Reverse

inches of mercury = atmospheres × 29.9213

Example: 10 inHg × 0.03342 = 0.3342 atm.

About both units

From

Inch of Mercury

inHg

The inch of mercury equals about 3386 Pa. Used in US barometers, US aviation altimeter settings and some engineering. Standard sea-level pressure: 29.92 inHg.

Real-world: Sea-level standard: 29.92 inHg. Mountain pass at 3000 m: ~21 inHg. US aviation QNH given in inHg.

Read full inch of mercury reference →

Atmosphere

atm

The standard atmosphere equals 101,325 pascals exactly — defined by CGPM in 1954. Represents average sea-level atmospheric pressure. Used in chemistry, aviation and engineering as a reference pressure.

Real-world: Sea-level pressure: 1 atm. Mount Everest summit: ~0.33 atm. Submarine at 100 m: ~11 atm.

Read full atmosphere reference →

Inch of Mercury to Atmosphere conversion table

Common inches of mercury to atmospheres values for quick reference.

Inch of Mercury (inHg)	Atmosphere (atm)
1 inHg	0.03342 atm
5 inHg	0.1671 atm
10 inHg	0.3342 atm
25 inHg	0.8355 atm
50 inHg	1.67105 atm
100 inHg	3.34211 atm
200 inHg	6.68421 atm
500 inHg	16.7105 atm
1,000 inHg	33.4211 atm
5,000 inHg	167.105 atm

Tips & common mistakes

Quick tips

1 inHg ≈ 3386 Pa ≈ 33.86 mbar.
29.92 inHg = 1013.25 mbar = 1 atm.
US pilots use inHg; European pilots use hPa (mbar).

Avoid these

Confusing inHg with mmHg — factor of 25.4.
Mixing US and European altimeter units on a single flight plan.
Using inHg on scientific papers — prefer Pa.

Frequently asked questions

How many atmospheres in a inch of mercury?

One inch of mercury equals 0.03342 atmospheres.

How do I convert inches of mercury to atmospheres?

Multiply the inch of mercury value by 0.03342 to get the equivalent in atmospheres.

What is 100 inches of mercury in atmospheres?

100 inches of mercury equals 3.34211 atmospheres.

Is a inch of mercury bigger than a atmosphere?

No. 1 inch of mercury equals 0.03342 atmospheres, so one inch of mercury is smaller.

How to convert inches of mercury to atmospheres without a calculator?

Multiply by 0.03 for a quick estimate; use a calculator for precise results.

Related pressure conversions

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