QNH Converter: hPa to inHg
1 inHg = 33.8639 hPa, so standard pressure of 29.92 inHg equals 1013.25 hPa (QNH 1013).
The result updates as you type or change units.
For general informational use. Verify critical aviation calculations and weather with an authoritative source.
hPa and inHg reference table
1 inHg = 33.8639 hPa. The table covers the range of pressures you are likely to see in METARs.
| hPa (QNH) | inHg (altimeter) |
|---|---|
| 980 | 28.94 |
| 990 | 29.23 |
| 1000 | 29.53 |
| 1005 | 29.68 |
| 1010 | 29.83 |
| 1013.25 (standard) | 29.92 |
| 1015 | 29.97 |
| 1020 | 30.12 |
| 1030 | 30.42 |
| 1040 | 30.71 |
How to spot each unit in a METAR
- Q1013: QNH in hectopascals, used in most of the world.
- A2992: altimeter setting in inches of mercury, used in the United States and some other countries. Read it as 29.92.
Why the unit matters: a real risk
Setting 29.92 when ATC says 992, or 992 hPa when you meant 29.92 inHg, gives wildly different altimeter readings, and some altimeters will accept a value in the wrong unit. Between 1000 hPa and 30.00 inHg, for example, there is about a 15.9 hPa difference, roughly 470 ft. Always confirm the unit as well as the number, especially when flying between countries that use different systems.
“High to low, look out below”
Flying from high pressure towards low pressure without resetting the altimeter makes it read higher than you really are. Each hPa is worth about 27–30 ft near sea level, so a 10 hPa drop leaves you about 300 ft lower than indicated. Learn more in QNH, QFE and QNE Explained.
QNH conversion between hPa and inHg
Aviation weather and altimeter settings are commonly expressed in hectopascals or inches of mercury. This converter helps when a report, procedure, aircraft instrument or study material uses a different pressure unit from the one you normally work with. The result is shown with practical precision rather than an unnecessarily long string of decimals.
How to use it
- Enter the pressure value.
- Choose hPa or inHg as the starting unit.
- Choose the other pressure unit as the destination.
- Use the swap control when you want to reverse the conversion.
Method and calculation
The conversion uses the standard relationship that one inch of mercury is approximately 33.8638867 hectopascals. Therefore hPa to inHg divides by that factor, while inHg to hPa multiplies by it.
Worked example and practical notes
A standard pressure near 1013.25 hPa converts to about 29.92 inHg. Operational weather and ATC information may use specific rounding conventions, so follow the value actually issued by the authoritative source.
This page is a unit converter, not a substitute for the current pressure setting issued for an aircraft operation.
Last reviewed: October 2026
Read the guide: QNH, QFE and QNE: Altimeter Settings Explained
Frequently asked questions
What is QNH?
QNH is an altimeter pressure setting that makes an altimeter indicate elevation above mean sea level when on the ground at the reference location, subject to standard altimetry assumptions.
How many hPa are in one inHg?
One inch of mercury is approximately 33.8639 hectopascals.
Why do some regions use inHg and others hPa?
Aviation pressure-setting conventions vary by country and operating environment.
Should I round the result?
Use the precision and rounding required by the authoritative weather report, ATC instruction or operating procedure.