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Vacuum

inHgtoatm

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

Factor1 inHg = 0.03342106 atm

Converter

inHg

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

Result
1.00263atm

Rendered to 6 significant figures.

Formula

Formula
atm = inHg × 0.03342106

Multiply any value in inches of mercury (vacuum) by 0.03342106 to obtain the value in standard atmospheres (vacuum).

Worked example

Convert 30 inHg to atm.

  1. 01Start with 30 inHg.
  2. 02Multiply by the conversion factor: 30 × 0.03342106 = 1.00263 atm.
Result30 inHg = 1.00263 atm

Conversion table

inHgatm
10.033421
20.066842
50.16711
100.33421
200.66842
501.6711
1003.3421
2006.6842
50016.711
100033.421

Reference values rounded to 5 significant figures for display.

FAQ

What is the conversion factor from inHg to atm?
1 inHg equals 0.03342106 atm. To convert, multiply the value in inches of mercury (vacuum) by 0.03342106.
How do I convert 1 inHg to atm?
1 inHg = 0.0334211 atm. For any value, multiply by 0.03342106.
How do I convert atm back to inHg?
Divide by the same factor — or equivalently, multiply by 29.92125. So 1 atm = 29.9213 inHg.
When would I need to convert inch of mercury (vacuum) to standard atmosphere (vacuum)?
Vacuum-pressure conversions between inHg and atm 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).

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