▸ processconvert
Vacuum

atmtoinHg

Convert standard atmospheres (vacuum) (atm) to inches of mercury (vacuum) (inHg).

Factor1 atm = 29.92125 inHg

Converter

atm

Accepts numbers or expressions, e.g. 150 + 14.7

Result
29.9213inHg

Rendered to 6 significant figures.

Formula

Formula
inHg = atm × 29.92125

Multiply any value in standard atmospheres (vacuum) by 29.92125 to obtain the value in inches of mercury (vacuum).

Worked example

Convert 1 atm to inHg.

  1. 01Start with 1 atm.
  2. 02Multiply by the conversion factor: 1 × 29.92125 = 29.9213 inHg.
Result1 atm = 29.9213 inHg

Conversion table

atminHg
129.921
259.843
5149.61
10299.21
20598.43
501496.1
1002992.1
2005984.3
50014961
100029921

Reference values rounded to 5 significant figures for display.

FAQ

What is the conversion factor from atm to inHg?
1 atm equals 29.92125 inHg. To convert, multiply the value in standard atmospheres (vacuum) by 29.92125.
How do I convert 1 atm to inHg?
1 atm = 29.9213 inHg. For any value, multiply by 29.92125.
How do I convert inHg back to atm?
Divide by the same factor — or equivalently, multiply by 0.03342106. So 1 inHg = 0.0334211 atm.
When would I need to convert standard atmosphere (vacuum) to inch of mercury (vacuum)?
Vacuum-pressure conversions between atm and inHg are common in vacuum-chamber instrumentation, pump-down endpoint specification, semiconductor and deposition process work, freeze-drying, electron-microscopy column pressure, vacuum metallurgy and HVAC / refrigeration service. Torr, mmHg and inHg dominate manometric vacuum gauges; mbar is standard on European instruments; micron Hg and mTorr cover high-vacuum work; Pa and kPa are the SI references. This category is vacuum / instrumentation intent — dimensionally the same as pressure, but kept separate so process-pressure searches and vacuum searches stay on the right page.
Is the conversion exact?
The factor shown is precise to at least 7 significant figures. For most process-engineering work this is far better than instrument accuracy. For metrology or trade applications, refer to the relevant national standard (NIST, BIPM, ISO 80000).

Related conversions