Convert Pressure from hectopascals to bar (hPa to bar)

hectopascal to bar Conversion Formula

Example

Let's convert 5 hectopascal (hPa) to bar (bar).

Using the formula:

Therefore, 5 hectopascal (hPa) is equal to 0.005 bar (bar).

How many hectopascals are in one bar? One bar (bar) contains 1000 hectopascals (hPa) — the inverse of the factor above. Multiplying by 0.001 takes you from hectopascals to bar; multiplying by 1000 brings you back.

Put in words: one hectopascal equals 0.001 bar, 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 bar (bar)?

The bar is a metric unit of pressure.

It is defined as exactly 100 kilopascals (kPa), or 100,000 Pascals (Pa).

Although it is not an official part of the International System of Units (SI), it is widely accepted for use with the SI. The bar is a popular unit for measuring pressure because it is very close to the average atmospheric pressure on Earth at sea level.

Origin of the Bar

The term "bar" comes from the Greek word βάρος (baros), which means "weight."

The unit was introduced by British meteorologist William Napier Shaw in 1909. It is still widely used in meteorology, oceanography, and engineering.

Bar vs. Standard Atmosphere (atm)

A common point of confusion is the difference between a bar and a standard atmosphere (atm).

While they are very close in value, they are not the same:

• 1 bar = 100,000 Pascals (Pa)
• 1 atmosphere (atm) = 101,325 Pascals (Pa)

This means 1 bar is approximately equal to 0.987 atm. Because it's so close to atmospheric pressure and is a round number (100 kPa), the bar is a very convenient unit for many applications.

Common Applications of the Bar

The bar is a versatile unit used to measure pressure in many industrial and everyday contexts.

Common examples include:

• Automotive: Measuring tire pressure (often listed on a car's door jamb alongside PSI).
• Scuba Diving: Expressing the amount of air pressure inside diving tanks.
• Weather: Used by meteorologists for weather forecasting and reading atmospheric pressure.
• Plumbing & Pumps: Measuring water pressure in pipes and pump systems.
• Industrial: Measuring air pressure in pneumatic equipment and gas pressure in cylinders for welding.

hectopascal to bar Conversion Table

Here are some quick reference conversions from hectopascal (hPa) to bar (bar):