PSI to inHg Converter
Convert pounds per square inch to inches of mercury — used for vacuum measurement. Results update as you type; exact factors shown.
One pound per square inch is 2.036 inches of mercury — see the exact factor, not a rounded rule of thumb.
How the psi to inhg converter works
Pressures convert through the pascal (1 N/m²). One bar is exactly 100 kPa; a standard atmosphere is exactly 101.325 kPa; 1 psi is 6.894757 kPa (a pound-force on a square inch); 1 mmHg is 133.322 Pa by the conventional definition.
The UK is metric for most trade and science but keeps miles, pints, stone and mpg (with the imperial gallon) in daily life.
Common pressure conversions
| From | To | Units |
|---|---|---|
| 0.5 psi | 1.018 inHg | pounds per square inch to inches of mercury |
| 1 psi | 2.036 inHg | pound per square inch to inches of mercury |
| 2 psi | 4.072 inHg | pounds per square inch to inches of mercury |
| 5 psi | 10.1801 inHg | pounds per square inch to inches of mercury |
| 10 psi | 20.3602 inHg | pounds per square inch to inches of mercury |
| 14.696 psi | 29.9214 inHg | pounds per square inch to inches of mercury |
| 15 psi | 30.5403 inHg | pounds per square inch to inches of mercury |
| 20 psi | 40.7204 inHg | pounds per square inch to inches of mercury |
| 25 psi | 50.9005 inHg | pounds per square inch to inches of mercury |
| 30 psi | 61.0806 inHg | pounds per square inch to inches of mercury |
| 50 psi | 101.801 inHg | pounds per square inch to inches of mercury |
| 100 psi | 203.602 inHg | pounds per square inch to inches of mercury |
Units in this converter and their exact factors
| Unit | Symbol | One unit in pascals |
|---|---|---|
| pascal | Pa | 1 pascal |
| kilopascal | kPa | 1,000 pascal |
| megapascal | MPa | 1,000,000 pascal |
| bar | bar | 100,000 pascal |
| millibar (hectopascal) | mbar | 100 pascal |
| standard atmosphere | atm | 101,325 pascal |
| pound per square inch | psi | 6,894.757293168 pascal |
| millimetre of mercury | mmHg | 133.322387415 pascal |
| inch of mercury | inHg | 3,386.389 pascal |
FAQFrequently asked questions about pressure conversion
How many inHg is 1 psi?
2.036 inHg.
What is 14.696 psi?
One atmosphere, which is 29.92 inHg.
Where is inHg used for vacuum?
Engine manifold vacuum and HVAC service gauges, where a reading of 25 inHg means 25 below atmospheric.
What is full vacuum in inHg?
29.92 inHg below atmospheric, at sea level.
What is 5 psi in inHg?
10.18 inHg.
Where these figures come from
- BIPM — The International System of Units (SI Brochure, 9th edition) — definitions of the base and derived units.
- NIST Special Publication 811 — Guide for the Use of the International System of Units — the exact conversion factors used here.
- National Physical Laboratory (NPL) — United Kingdom's national measurement authority.
Last checked: September 2026. Conversion factors are fixed by definition and do not change with tax years or regulations.