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To convert from Inch of mercury (inHg) to meter of water @ 4°C (mH2O), use the following formula:
With is the ratio between the base units kilopascal (kPa) and kilopound per square inch (ksi).
Let's convert 5 Inch of mercury (inHg) to meter of water @ 4°C (mH2O).
Using the formula:
Therefore, 5 Inch of mercury (inHg) is equal to meter of water @ 4°C (mH2O).
Here are some quick reference conversions from Inch of mercury (inHg) to meter of water @ 4°C (mH2O):
| Inches of mercury | meters of water @ 4°C |
|---|---|
| 0.000001 inHg | mH2O |
| 0.001 inHg | mH2O |
| 0.1 inHg | mH2O |
| 1 inHg | mH2O |
| 2 inHg | mH2O |
| 3 inHg | mH2O |
| 4 inHg | mH2O |
| 5 inHg | mH2O |
| 6 inHg | mH2O |
| 7 inHg | mH2O |
| 8 inHg | mH2O |
| 9 inHg | mH2O |
| 10 inHg | mH2O |
| 20 inHg | mH2O |
| 30 inHg | mH2O |
| 40 inHg | mH2O |
| 50 inHg | mH2O |
| 100 inHg | mH2O |
| 1000 inHg | mH2O |
| 10000 inHg | mH2O |
For all Pressure converters, choose units using the From/To dropdowns above.
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:
A meter of water @ 4°C (mH2O) is a metric unit used to measure pressure.
It is precisely defined as 9.80665 kilopascals (kPa).
The specific temperature of 4°C (39.2°F) is key because this is the point where pure water is at its heaviest or most dense (approximately 999.972 kg/m3).
Using this temperature provides a stable and reliable standard for defining pressure.
This precision is essential in scientific and engineering fields like hydraulics and fluid mechanics, ensuring that measurements of pressure head are consistent and accurate across different applications and locations.
The unit "meter of water" (mH2O) is frequently used in civil engineering, hydrology, and irrigation to measure water levels and pressure.
It provides an intuitive way to express the pressure exerted by a column of water, such as the water level in a reservoir, dam, or groundwater well. This measurement is sometimes referred to as the 'piezometric head'.
It is also commonly used to specify the performance of pumps, indicating the height to which a pump can lift water.
For practical use, it's often helpful to know how mH2O converts to other common pressure units.
One mH2O is equal to:
These conversion factors allow engineers and scientists to easily translate pressure specifications between different international and imperial systems.