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To convert from millimeter of mercury (mmHg) to hectopascal (hPa), use the following formula:
hectopascal (hPa)
= 0.133322 × 10× millimeter of mercury (mmHg)
= 1.33322× millimeter of mercury (mmHg)
Let's convert 5 millimeter of mercury (mmHg) to hectopascal (hPa).
Using the formula:
5 × 1.33322 = 6.6661
Therefore, 5 millimeter of mercury (mmHg) is equal to 6.6661 hectopascal (hPa).
How many millimeters of mercury are in one hectopascal? One hectopascal (hPa) contains 0.7500637554192106329 millimeters of mercury (mmHg) — the inverse of the factor above. Multiplying by 1.33322 takes you from millimeters of mercury to hectopascals; multiplying by 0.7500637554192106329 brings you back.
Put in words: one millimeter of mercury equals 1.33322 hectopascals, so the millimeter of mercury is the larger unit of this pair. Converting between them never changes the amount of pressure being measured — only the size of the unit you count it in.
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 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:
Here are some quick reference conversions from millimeter of mercury (mmHg) to hectopascal (hPa):
| millimeters of mercury | hectopascals |
|---|---|
| 0.000001 mmHg | 0.00000133322 hPa |
| 0.001 mmHg | 0.00133322 hPa |
| 0.1 mmHg | 0.133322 hPa |
| 1 mmHg | 1.33322 hPa |
| 2 mmHg | 2.66644 hPa |
| 3 mmHg | 3.99966 hPa |
| 4 mmHg | 5.33288 hPa |
| 5 mmHg | 6.6661 hPa |
| 6 mmHg | 7.99932 hPa |
| 7 mmHg | 9.33254 hPa |
| 8 mmHg | 10.66576 hPa |
| 9 mmHg | 11.99898 hPa |
| 10 mmHg | 13.3322 hPa |
| 20 mmHg | 26.6644 hPa |
| 30 mmHg | 39.9966 hPa |
| 40 mmHg | 53.3288 hPa |
| 50 mmHg | 66.661 hPa |
| 100 mmHg | 133.322 hPa |
| 1000 mmHg | 1333.22 hPa |
| 10000 mmHg | 13332.2 hPa |
For all Pressure converters, choose units using the From/To dropdowns above.