Choose a Measurement
Select a measurement and convert between different units
Single conversion
To convert from hectopascal (hPa) to Inch of mercury (inHg), use the following formula:
With is the ratio between the base units kilopound per square inch (ksi) and kilopascal (kPa).
Let's convert 5 hectopascal (hPa) to Inch of mercury (inHg).
Using the formula:
Therefore, 5 hectopascal (hPa) is equal to Inch of mercury (inHg).
Here are some quick reference conversions from hectopascal (hPa) to Inch of mercury (inHg):
| hectopascals | Inches of mercury |
|---|---|
| 0.000001 hPa | inHg |
| 0.001 hPa | inHg |
| 0.1 hPa | inHg |
| 1 hPa | inHg |
| 2 hPa | inHg |
| 3 hPa | inHg |
| 4 hPa | inHg |
| 5 hPa | inHg |
| 6 hPa | inHg |
| 7 hPa | inHg |
| 8 hPa | inHg |
| 9 hPa | inHg |
| 10 hPa | inHg |
| 20 hPa | inHg |
| 30 hPa | inHg |
| 40 hPa | inHg |
| 50 hPa | inHg |
| 100 hPa | inHg |
| 1000 hPa | inHg |
| 10000 hPa | inHg |
For all Pressure converters, choose units using the From/To dropdowns above.
A hectopascal (hPa) is a metric unit used to measure pressure.
You will most commonly see it in weather reports to describe atmospheric pressure (also known as barometric pressure).
If you've seen millibars (mbar) on older weather maps, the hectopascal is its modern replacement.
The switch was simple for meteorologists because the units are exactly the same (1 hPa = 1 mbar).
The hectopascal is now the international standard for measuring atmospheric pressure, making weather data consistent worldwide.
The conversion is in the name. The prefix "hecto-" means 100. This makes the math simple:
Just as "hecto-" means 100, "kilo-" means 1,000. This defines their relationship:
An inch of mercury, often abbreviated as inHg, is a unit of pressure.
It is not part of the standard metric (SI) system but is widely used in the United States and in specific fields like meteorology and aviation.
The unit is defined by its name: it is the amount of pressure exerted by a column of liquid mercury exactly one inch tall at a standard temperature.
You will most commonly encounter inches of mercury in a few key areas:
Weather Reporting: In the U.S., inHg is the standard unit for reporting barometric pressure (also known as atmospheric pressure).
A "high" pressure system indicating clear weather might be around 30.50 inHg, while a "low" pressure system associated with storms could be 28.50 inHg.
Aviation: This measurement is critical for pilot safety.
Pilots use the local barometric pressure (in inHg) to calibrate their altimeters—instruments that measure altitude—to ensure they are flying at the correct height.
Vacuum Systems: The unit is also widely used in science and industry to measure vacuum pressure.
This is common in systems like air conditioning, refrigeration, and for monitoring the manifold pressure in piston engines.
Because inHg is not a global standard, it's often necessary to convert it to other pressure units for calculations or international use.
Here are the most common conversions for 1 inHg: