How to convert inches of mercury to hectopascals
One inch of mercury equals 33.8639 hectopascals, so multiply the number of inches of mercury by 33.8639:
hPa = inHg × 33.8639
inHg = hPa ÷ 33.8639 (1 hPa = 0.02953 inHg)
Example: 29 inHg → 29 × 33.8639 = 982.053 hPa.
Going the other way, divide by 33.8639, or multiply by 0.02953; the hectopascals to inches of mercury converter does it for you.
Everyday values
| Inches of mercury | Hectopascals | For example |
|---|---|---|
| 29 inHg | 982.053 hPa | low pressure, unsettled weather |
| 29.92 inHg | 1,013.21 hPa | standard pressure |
| 30.5 inHg | 1,032.85 hPa | high pressure |
When you need this conversion
Multiply inches of mercury by 33.864 to get hectopascals. Pilots set their altimeter to the local pressure, given in inHg in the US and Canada and in hPa in most other countries.
Inch of mercury to hectopascal conversion table
| inHg | hPa | inHg | hPa |
|---|---|---|---|
| 28.5 inHg | 965.121 hPa | 29.7 inHg | 1,005.76 hPa |
| 28.6 inHg | 968.507 hPa | 29.8 inHg | 1,009.14 hPa |
| 28.7 inHg | 971.894 hPa | 29.9 inHg | 1,012.53 hPa |
| 28.8 inHg | 975.28 hPa | 30 inHg | 1,015.92 hPa |
| 28.9 inHg | 978.666 hPa | 30.1 inHg | 1,019.3 hPa |
| 29 inHg | 982.053 hPa | 30.2 inHg | 1,022.69 hPa |
| 29.1 inHg | 985.439 hPa | 30.3 inHg | 1,026.08 hPa |
| 29.2 inHg | 988.826 hPa | 30.4 inHg | 1,029.46 hPa |
| 29.3 inHg | 992.212 hPa | 30.5 inHg | 1,032.85 hPa |
| 29.4 inHg | 995.598 hPa | 30.6 inHg | 1,036.24 hPa |
| 29.5 inHg | 998.985 hPa | 30.7 inHg | 1,039.62 hPa |
| 29.6 inHg | 1,002.37 hPa | 30.8 inHg | 1,043.01 hPa |
About the units
- Inch of mercury (inHg): the pressure of a 1-inch column of mercury, about 3,386.39 Pa.
- Hectopascal (hPa): 100 pascals, identical to the millibar used in weather reports.
Both are units of pressure. The conversion factor comes from the exact definitions above, so the calculator is exact; results are only rounded for display (up to six significant digits).
Frequently asked questions
How many hectopascals are in one inch of mercury?
One inch of mercury is 33.8639 hectopascals. One hectopascal is 0.02953 inches of mercury.
How do I convert inches of mercury to hectopascals?
Multiply the value in inches of mercury by 33.8639. To go back, divide by 33.8639.
What is 29 inHg in hectopascals?
29 inHg = 982.053 hPa.
What is 29.92 inHg in hectopascals?
29.92 inHg = 1,013.21 hPa.
Sources
- NIST Special Publication 811 (2008), Guide for the Use of the International System of Units (SI), Appendix B: conversion factors.
- NIST Handbook 44 (2024), Appendix C: General tables of units of measurement.
Last reviewed 5 October 2026. Results are estimates; see our disclaimer.