Convert Pressure from Inches of mercury to pascals (inHg to Pa)

Inch of mercury to pascal Conversion Formula

Example

Let's convert 5 Inch of mercury (inHg) to pascal (Pa).

Using the formula:

Therefore, 5 Inch of mercury (inHg) is equal to 16931.944766305439265 pascal (Pa).

How many inches of mercury are in one pascal? One pascal (Pa) contains 0.00029529980572284863811 Inches of mercury (inHg) — the inverse of the factor above. Multiplying by 3386.3889532610878529 takes you from inches of mercury to pascals; multiplying by 0.00029529980572284863811 brings you back.

Put in words: one inch of mercury equals 3386.3889532610878529 pascals, so the inch 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.

What is an Inch of Mercury (inHg)?

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.

Where is inHg Used?

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.

How to Convert inHg to Other Pressure Units

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:

• 0.491154 pounds per square inch (PSI)
• 33.86 millibars (mbar)
• 3,386.39 pascals (Pa)
• 0.000491154 kilopound per square inch (ksi)

What is a Pascal (Pa)?

A pascal (Pa) is the standard unit of pressure in the International System of Units (SI). It is a derived unit, meaning other base units define it.

The primary pascal definition is one newton of force applied over an area of one square meter (1 Pa = 1 N/m²).

Because a single pascal represents a very small amount of pressure, it is most often seen in multiples.

The most common multiples are the kilopascal (kPa), equal to 1,000 pascals, and the megapascal (MPa), equal to 1,000,000 pascals.

These units are widely used in fields from weather forecasting to material science.

Who is the Pascal Unit Named After?

The pascal (Pa) unit is named in honor of Blaise Pascal, a key 17th-century French mathematician, physicist, and inventor.

His groundbreaking work on how fluids behave under pressure (known as hydrodynamics and hydrostatics) and his formulation of Pascal's Law were essential to our modern understanding of pressure.

Understanding the Scale of a Pascal in Real Life

To understand just how small a single pascal is, here are two real-world examples:

• A dollar bill: The gentle pressure of a single U.S. dollar bill resting flat on a table is about 1 Pa.
• Atmospheric pressure: The standard atmospheric pressure you feel at sea level is approximately 101,325 pascals (or 101.3 kPa).

This shows why, for most everyday measurements (like tire pressure or weather), the larger kilopascal (kPa) is much more practical.

Inch of mercury to pascal Conversion Table

Here are some quick reference conversions from Inch of mercury (inHg) to pascal (Pa):