Hectopascals to Inches of Mercury (hPa to inHg)
1 hPa = 0.02953 inHg. Turn hPa or millibar pressures from weather maps and ICAO altimeter settings into inches of mercury, with both charts.
Inch of Mercury (inHg) = Hectopascal (hPa) × 0.029529983301
Hectopascal (hPa): A hectopascal (hPa) is 100 pascals, identical to one millibar. A standard atmosphere is exactly 1013.25 hPa, while a measured atmospheric pressure can differ from that reference.
Inch of Mercury (inHg): The conventional inch of mercury selected here is 25.4 conventional mmHg, or 3,386.388640341 Pa. A physical mercury column depends on temperature, density and gravity; one standard atmosphere is about 29.9213 inHg under this convention.
| Hectopascal (hPa) | Inch of Mercury (inHg) |
|---|---|
| 1 | 0.029529983301 |
| 5 | 0.147649916505 |
| 10 | 0.29529983301 |
| 25 | 0.738249582525 |
| 50 | 1.47649916505 |
| 100 | 2.9529983301 |
Most of the world gives air pressure in hectopascals, which are identical to the millibars on weather maps, while US and Canadian pilots set their altimeters in inches of mercury and US weather broadcasts quote the barometer the same way. The standard atmosphere links the two: 1013.25 hPa, or 29.92 inHg as it is usually rounded.
A pilot flying from Europe to North America switches from a QNH such as 1008 hPa to an altimeter setting such as 29.77 inHg, and at or above 18,000 feet in the US every aircraft sets 29.92. Forecasters and storm watchers convert the other way when a hurricane's central pressure is announced in millibars.
How to use this tool
- Type a value in the Hectopascal box to see it in inches of mercury, or type in the Inch of Mercury box to convert the other way.
- Press ⇄ to swap the two units, or Load example for a typical value.
- Check the charts below for common values; for other units, open the Pressure converter.
Formula
Inch of Mercury (inHg) = Hectopascal (hPa) × 0.029529983301
Hectopascal (hPa) = Inch of Mercury (inHg) × 33.8638864034
Both factors come from exact definitions: 1 inch of mercury = 33.8638864034 hectopascals and 1 hectopascal = 0.029529983301 inches of mercury (shown to 12 significant digits).
Example
Two conversions worked with the same factors the converter uses:
1013 hPa × 0.029529983301 ≈ 29.9139 inHg
29.92 inHg × 33.8638864034 ≈ 1013.21 hPa
Hectopascal to Inch of Mercury chart
Common values from hectopascals to inches of mercury, rounded to four decimal places.
| Hectopascal (hPa) | Inch of Mercury (inHg) |
|---|---|
| 850 | 25.1005 |
| 900 | 26.577 |
| 950 | 28.0535 |
| 960 | 28.3488 |
| 970 | 28.6441 |
| 980 | 28.9394 |
| 990 | 29.2347 |
| 995 | 29.3823 |
| 1,000 | 29.53 |
| 1,005 | 29.6776 |
| 1,008 | 29.7662 |
| 1,010 | 29.8253 |
| 1,012 | 29.8843 |
| 1,013.25 | 29.9213 |
| 1,015 | 29.9729 |
| 1,018 | 30.0615 |
| 1,020 | 30.1206 |
| 1,025 | 30.2682 |
| 1,030 | 30.4159 |
| 1,035 | 30.5635 |
| 1,040 | 30.7112 |
| 1,050 | 31.0065 |
Inch of Mercury to Hectopascal chart
The reverse direction for values people often look up.
| Inch of Mercury (inHg) | Hectopascal (hPa) |
|---|---|
| 28.5 | 965.1208 |
| 29 | 982.0527 |
| 29.5 | 998.9846 |
| 29.7 | 1,005.76 |
| 29.8 | 1,009.14 |
| 29.9 | 1,012.53 |
| 29.92 | 1,013.21 |
| 30 | 1,015.92 |
| 30.1 | 1,019.3 |
| 30.2 | 1,022.69 |
| 30.5 | 1,032.85 |
| 31 | 1,049.78 |
Pressures meteorologists quote in hPa
| Reading | Hectopascal (hPa) | Inch of Mercury (inHg) |
|---|---|---|
| 300 hPa chart, near jet-stream level | 300 | 8.859 |
| 500 hPa chart, roughly 5.6 km above sea level | 500 | 14.765 |
| 850 hPa chart, roughly 1.5 km above sea level | 850 | 25.1005 |
| Typhoon Tip (1979), lowest sea-level pressure recorded | 870 | 25.6911 |
| Hurricane Wilma (2005), Atlantic record low | 882 | 26.0454 |
| ICAO standard atmosphere at sea level | 1,013.25 | 29.9213 |
Quick mental estimate
Start from 1013 hPa = 29.92 inHg and move 0.03 inHg for every hectopascal: 1000 hPa → 29.92 − 0.39 = 29.53 inHg. The 0.03 step is about 1.6% above the true 0.02953, which keeps the estimate within about 0.03 inHg between 950 and 1050 hPa.
Use the converter or the charts when the exact figure matters.
The two units
Hectopascal (hPa): A hectopascal (hPa) is 100 pascals, identical to one millibar. A standard atmosphere is exactly 1013.25 hPa, while a measured atmospheric pressure can differ from that reference.
Inch of Mercury (inHg): The conventional inch of mercury selected here is 25.4 conventional mmHg, or 3,386.388640341 Pa. A physical mercury column depends on temperature, density and gravity; one standard atmosphere is about 29.9213 inHg under this convention.
Frequently asked questions
Is a hectopascal the same as a millibar?
Yes. One hectopascal is 100 pascals and one millibar is a thousandth of a bar, also 100 pascals, so readings such as 1013 hPa and 1013 mb are identical.
What is 1000 hPa in inches of mercury?
1000 hPa is about 29.53 inHg. That is a fairly low reading at sea level, below the standard 1013.25 hPa, and the kind of pressure found in many low-pressure systems.
Why does the US use inches of mercury for altimeters?
US aviation and weather reporting kept the mercury-barometer unit, and the FAA's procedures are written in it, including the 29.92 standard setting for flight at and above 18,000 feet. Countries using hPa follow the same method with 1013.25 as the standard value.
How precise is the result?
The converter uses the exact definitions above with browser floating-point arithmetic and shows up to 12 significant digits. The charts round to four decimal places for reading.
Sources
Last updated:
Page address with these inputs: https://kakao.mobile/tools/hectopascal-to-inhg-converter/
Cite or embed this tool
kakaoCalc. (2026, November 8). Hectopascals to Inches of Mercury (hPa to inHg). https://kakao.mobile/tools/hectopascal-to-inhg-converter/
“Hectopascals to Inches of Mercury (hPa to inHg).” kakaoCalc, 8 Nov. 2026, kakao.mobile/tools/hectopascal-to-inhg-converter/.
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