Inches of mercury.
inHgs to PSI Converter — inHg to psi
Convert inHg (inHg) to PSI (psi) using the exact conversion factor (1 inhg = 0.4911541996 psi). See the formula, worked examples, conversion table, history, and common uses.
inHgs to PSI converter
Converter
Engineering Converter
Convert common stress, force, torque, power, and energy units used in engineering.
Context values
Some unit families need one extra value for a physically accurate result.
Pounds per square inch.
Result = input x 3386.389 / 6894.757293.
Stress Pressure units are compatible.
Reserved above the conversion cards and below the converter.
About Converting inHgs to PSI
inHg and PSI both measure a quantity used in structural or mechanical engineering — commonly stress, pressure, force, torque, power, or energy — where converting between the unit conventions used in different regions, industries, or equipment specifications is a routine part of design work. Specifically: Inches of mercury, and pounds per square inch.
Formula
psi = inhgs × 0.491154199634
This factor comes from each unit's defined relationship to the category's base unit: 1 inhg equals 3386.389 base units, and 1 psi equals 6894.75729317 base units, so dividing one by the other gives the direct inhg-to-psi factor of 0.491154199634.
Simple example
1 inHg × 0.4911541996 = 0.4911541996 psi
1 inhg = 0.4911541996 psi.
Real-world example
100 inHg × 0.4911541996 = 49.11541996 psi
100 inhgs = 49.11541996 psi.
Conversion table
| inHg (inHg) | PSI (psi) |
|---|---|
| 1 inHg | 0.4911541996 psi |
| 10 inHg | 4.911541996 psi |
| 50 inHg | 24.55770998 psi |
| 100 inHg | 49.11541996 psi |
| 500 inHg | 245.5770998 psi |
| 1,000 inHg | 491.1541996 psi |
Reverse conversion: PSI to inHg
0.4911541996 psi × 2.036020461 = 0.9999999999 inHg
0.4911541996 psi = 0.9999999999 inhgs.
inhgs = psi × 2.03602046108
For a page dedicated to this direction, see PSI to inHg.
Understanding the inHg (inHg)
Inches of mercury.
Understanding the PSI
PSI (psi) measures pressure. PSI (pounds-force per square inch) equals exactly 6,894.757293168 pascals. It is classified as a US/imperial customary unit.
Where it's used: United States (standard pressure unit for tires, tools, and plumbing)
Uses of the PSI today
- Tire pressure specifications in the US
- Hydraulic and pneumatic system ratings
- Plumbing, compressed-air tools, and industrial equipment ratings
History of the PSI
PSI is a derived unit from the pound-force and the inch, both themselves standardized through English and later international agreements rather than invented as a pressure unit from scratch.
It became the default pressure unit in US engineering as pound-force and inch-based measurement dominated American industry through the 19th and 20th centuries, and it remains in everyday use for tires and tools even as most other measurements in the US context stay imperial.
Historical origin. PSI was not the invention of a single named person; it developed through the process described above.
PSI — sources
- NIST Special Publication 811 — Guide for the Use of the International System of Units — Documents conversion factors for psi and other US customary pressure units.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many psi are in 1 inhg?
1 inhg equals 0.4911541996 psi, using the exact defined conversion factor rather than an estimate.
How do I convert inhg to psi?
Multiply the inhg value by 0.4911541996. The converter above does this instantly to whatever precision you set.
How do I convert psi back to inhg?
Use the reverse factor: 1 psi equals 2.036020461 inhgs. You can also use the swap control in the converter above to flip the direction instantly.
What is a inhg?
inHg (inHg) is a unit of engineering.
What is a psi?
PSI (psi) measures pressure. PSI (pounds-force per square inch) equals exactly 6,894.757293168 pascals. It is classified as a US/imperial customary unit.
Is the inhg to psi conversion exact?
Yes. PSI (pounds-force per square inch) equals exactly 6,894.757293168 pascals. That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.
Why do engineering unit conventions vary so much by region and industry?
Pressure, force, and stress can be expressed in metric (pascal, newton), US customary (psi, pound-force), or older and industry-specific units (atmosphere, torr, kip) depending on the country, industry, and even the equipment manufacturer, which is why engineers routinely need to convert between them when working across specs from different sources.