Pressure converter
Converts pressures: inHg, hPa, mbar, Pa, kPa, bar, psi, mmHg, and atm.
29.92 inHg is 1,013.2076 hPa.
- Input
Provenance
- Computed by
- units.pressure.convert 1.0.0, core 0.1.0
- Model
- Exact unit definitions
- Accuracy
- Exact to double precision: each conversion is one correctly rounded ratio of exact definitions
- Notes
- None
- Cites
- National Institute of Standards and Technology, Guide for the Use of the International System of Units (SI), NIST Special Publication 811; International Civil Aviation Organization, Annex 5 to the Convention on International Civil Aviation: Units of Measurement to be Used in Air and Ground Operations
Something look off?
How we got thisFormula, worked example, sources, and proof
Model: Exact unit definitions
Accuracy: Exact to double precision: each conversion is one correctly rounded ratio of exact definitions
When to use this: Use this wherever a pressure has to cross between the systems that report it: an altimeter setting in inches of mercury against a QNH in hectopascals, a tyre or hydraulic pressure in psi against a gauge in bar, a blood-pressure or manometer reading in millimetres of mercury against pascals. Aviation runs on inHg in North America and hPa almost everywhere else, and the two appear side by side on the same flight.
Limitations: This converts the size of a pressure and not what it is measured against: it cannot tell absolute pressure from gauge pressure, and a psi that meant psig is still 14.7 psi away from what it looks like here. The mercury units are the conventional ones -- inHg is exactly 3386.389 Pa and mmHg exactly 133.322387415 Pa by definition, not mercury weighed at a particular temperature -- so a laboratory manometer corrected for its own mercury will differ in the seventh digit. Altitude, standard atmospheres and pressure altitude are the atmosphere tools, not this.
Worked example: 29.92 inHg in hPa. Source: Exact unit definitions (NIST SP 811 Appendix B). It is golden test vector v001, and every build checks the tool still gives its answer within its tolerance.
You enter
- To unit
- hPa
- Value
- 29.92 inHg
You get
- Converted
- 1,013.2076 hPa
- Input
- 29.92 inHg
Review: Not yet independently reviewed by a metrologist.
Last verified: 2026-09-18, when a maintainer last confirmed this tool's sources at the issuer. See the sources ledger.
Status: version 1.0.0, core 0.1.0. See this tool in the verification report.
Checked against: 73 golden test vectors (download the test vectors, each with its source and tolerance). See how results are checked and every source.
Sources
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811, National Institute of Standards and Technology, 2008 edition. Appendix B.8, Factors for units listed alphabetically.
- Annex 5 to the Convention on International Civil Aviation: Units of Measurement to be Used in Air and Ground Operations, International Civil Aviation Organization, 5th edition. Chapter 3 and Table 3-3. Paid only.