Convert Pressure from hectopascals to millimeters of mercury (hPa to mmHg)

hectopascal to millimeter of mercury Conversion Formula

Example

Let's convert 5 hectopascal (hPa) to millimeter of mercury (mmHg).

Using the formula:

Therefore, 5 hectopascal (hPa) is equal to 3.7503187770960531645 millimeter of mercury (mmHg).

How many hectopascals are in one millimeter of mercury? One millimeter of mercury (mmHg) contains 1.33322 hectopascals (hPa) — the inverse of the factor above. Multiplying by 0.7500637554192106329 takes you from hectopascals to millimeters of mercury; multiplying by 1.33322 brings you back.

Put in words: one hectopascal equals 0.7500637554192106329 millimeters of mercury, so the hectopascal is the smaller 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.

What is a hectopascal (hPa)?

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).

Hectopascal vs. Millibar: Which is it?

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.

How to Convert Hectopascals to Pascals (hPa to Pa)

The conversion is in the name. The prefix "hecto-" means 100. This makes the math simple:

• 1 hectopascal (hPa) = 100 pascals (Pa)

How to Convert Hectopascals to Kilopascals (hPa to kPa)

Just as "hecto-" means 100, "kilo-" means 1,000. This defines their relationship:

• 1 hectopascal (hPa) = 0.1 kilopascals (kPa)
• 10 hectopascals (hPa) = 1 kilopascal (kPa)

What Is a Millimeter of Mercury (mmHg)?

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 Origin of the mmHg Unit

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.

Common Applications of mmHg

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.

How to Convert mmHg to Other Pressure Units

While mmHg is common, other pressure units are standard in different fields. Here are the most common conversions:

• 1 mmHg = 133.322 pascals (Pa)
• 1 mmHg = 0.133322 kilopascals (kPa)
• 760 mmHg = 1 standard atmosphere (atm)

hectopascal to millimeter of mercury Conversion Table

Here are some quick reference conversions from hectopascal (hPa) to millimeter of mercury (mmHg):