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To convert from millimeter of mercury (mmHg) to millibar (mbar), use the following formula:
Let's convert 5 millimeter of mercury (mmHg) to millibar (mbar).
Using the formula:
Therefore, 5 millimeter of mercury (mmHg) is equal to millibar (mbar).
Here are some quick reference conversions from millimeter of mercury (mmHg) to millibar (mbar):
| millimeters of mercury | millibar |
|---|---|
| 0.000001 mmHg | mbar |
| 0.001 mmHg | mbar |
| 0.1 mmHg | mbar |
| 1 mmHg | mbar |
| 2 mmHg | mbar |
| 3 mmHg | mbar |
| 4 mmHg | mbar |
| 5 mmHg | mbar |
| 6 mmHg | mbar |
| 7 mmHg | mbar |
| 8 mmHg | mbar |
| 9 mmHg | mbar |
| 10 mmHg | mbar |
| 20 mmHg | mbar |
| 30 mmHg | mbar |
| 40 mmHg | mbar |
| 50 mmHg | mbar |
| 100 mmHg | mbar |
| 1000 mmHg | mbar |
| 10000 mmHg | mbar |
For all Pressure converters, choose units using the From/To dropdowns above.
A millimeter of mercury (mmHg) is a manometric unit of pressure.
It was historically defined as the pressure generated by a column of mercury exactly one millimeter high.
Today, it is most famous as the unit used in medicine for measuring blood pressure. It is also commonly used in meteorology, aviation, and physics to measure atmospheric pressure or vacuum pressure.
The mmHg unit originates from the invention of the barometer by Evangelista Torricelli in 1643.
Torricelli's device measured atmospheric pressure by seeing how high it could support a column of mercury in a tube.
Standard atmospheric pressure was found to support a column approximately 760 mm high, which established 760 mmHg as a standard reference point.
The most well-known application of mmHg is in medicine.
Blood Pressure: Readings are given as two numbers: systolic pressure (when the heart beats) over diastolic pressure (when the heart rests), such as 120/80 mmHg. This is a critical vital sign for human health.
Meteorology: Used for reporting barometric (atmospheric) pressure, which helps in weather forecasting.
Physics & Engineering: Used for measuring vacuum pressures and other low-pressure systems where precision is needed.
While mmHg is common, other pressure units are standard in different fields. Here are the most common conversions:
A millibar (mbar) is a metric unit used to measure atmospheric pressure.
It's most commonly used in weather forecasting and reporting.
(Technically, one millibar is equal to 0.1 kilopascal, or kPa).
Meteorologists use millibars as the primary unit to measure and report atmospheric pressure.
On weather maps, you'll see lines called isobars, which connect areas of equal pressure, drawn in millibar intervals.
Standard atmospheric pressure at sea level is about 1013 mbar.
This number is a key benchmark for weather conditions:
Yes, for all practical purposes, a millibar (mbar) and a hectopascal (hPa) are the same.
The two units are used interchangeably.
The conversion is simple: 1 mbar = 1 hPa.
While you'll still see millibars in public weather reports (especially in the U.S.), the hectopascal is the preferred SI (International System of Units) unit for global scientific consistency.
A barometer measures barometric pressure—the weight of the air above you—using millibars.
Watching the change in this reading is key to predicting the weather: