inHg to psi Converter
Convert inches of mercury (inHg) to pounds per square inch (psi) for vacuum, HVAC, automotive boost, and aviation instruments. Choose your reference condition to match your table.
Pick the one used in your manual/table.
Quick results
Formulas
1 inHg (32°F) = 3386.389 Pa = 0.491097 psi
1 inHg (60°F) = 3376.85 Pa ≈ 0.48977 psi
psi = inHg × factor_psi
inHg = psi ÷ factor_psi
If your source does not specify temperature, 0°C/32°F is a safe default. Some industrial/aviation charts use 60°F — hence the toggle above.
inHg → psi table (32°F)
| inHg | psi | kPa |
|---|
Values use 0°C/32°F factor. For 60°F, results are ≈0.27% lower.
Where is inHg used?
You’ll see inches of mercury on barometers, vacuum gauges, some HVAC/AC service manuals, and occasionally in aviation altimetry/pressure discussions (though inHg there is often used as a pressure reading, not a column of mercury).
Why convert to psi?
psi is the “common language” for mechanics, automotive boost/vacuum, pneumatics and many US industrial systems. Converting brings the reading into the same unit as your other instruments.
Tips
- Check your reference temperature.
- State gauge vs absolute if you’re reporting to others.
- For vacuum work, note that 29.92 inHg ≈ 14.7 psi ≈ 1 atm.
FAQ
1. Is 29.92 inHg really 14.7 psi?
Yes — at standard atmosphere (0°C), 29.92 inHg corresponds to 1 atm ≈ 14.6959 psi. That’s why the factor is ~0.4911.
2. Why do calculators give slightly different results?
They may be using 32°F vs 60°F, or using rounded values for atmospheric pressure. Our tool shows both.
Formula (LaTeX) + variables + units
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1 inHg (32°F) = 3386.389 Pa = 0.491097 psi 1 inHg (60°F) = 3376.85 Pa ≈ 0.48977 psi psi = inHg × factor_psi inHg = psi ÷ factor_psi
- No variables provided in audit spec.
- NIST — Weights and measures — nist.gov · Accessed 2026-01-19
https://www.nist.gov/pml/weights-and-measures - NIST — SI units — nist.gov · Accessed 2026-01-19
https://www.nist.gov/pml/owm/metric-si/si-units
Last code update: 2026-01-19
- Initial audit spec draft generated from HTML extraction (review required).
- Verify formulas match the calculator engine and convert any text-only formulas to LaTeX.
- Confirm sources are authoritative and relevant to the calculator methodology.