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Vacuum

inHgtommHg

Convert inches of mercury (vacuum) (inHg) to millimetres of mercury (vacuum) (mmHg).

Factor1 inHg = 25.4 mmHg

Converter

inHg

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

Result
762mmHg

Rendered to 6 significant figures.

Formula

Formula
mmHg = inHg × 25.4

Multiply any value in inches of mercury (vacuum) by 25.4 to obtain the value in millimetres of mercury (vacuum).

Worked example

Convert 30 inHg to mmHg.

  1. 01Start with 30 inHg.
  2. 02Multiply by the conversion factor: 30 × 25.4 = 762 mmHg.
Result30 inHg = 762 mmHg

Conversion table

inHgmmHg
125.4
250.8
5127
10254
20508
501270
1002540
2005080
50012700
100025400

Reference values rounded to 5 significant figures for display.

FAQ

What is the conversion factor from inHg to mmHg?
1 inHg equals 25.4 mmHg. To convert, multiply the value in inches of mercury (vacuum) by 25.4.
How do I convert 1 inHg to mmHg?
1 inHg = 25.4 mmHg. For any value, multiply by 25.4.
How do I convert mmHg back to inHg?
Divide by the same factor — or equivalently, multiply by 0.03937007. So 1 mmHg = 0.0393701 inHg.
When would I need to convert inch of mercury (vacuum) to millimetre of mercury (vacuum)?
Vacuum-pressure conversions between inHg and mmHg 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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