Instrumentation Calculators

# PSIG to PSIA Conversion Calculator

Pressure measurements are a fundamental aspect of various process engineering and instrumentation and control applications. Pressure is typically measured in two main forms: PSIG (pounds per square inch gauge) and PSIA (pounds per square inch absolute).

This calculator helps you convert PSIG to PSIA accurately.

PSIG(Pounds per Square Inch Gauge) is a measure of pressure relative to the ambient atmospheric pressure. This means that it only considers the pressure in excess of the atmospheric pressure around us. For example, if a tire gauge shows 30 PSIG, it means the pressure inside the tire is 30 PSI above the atmospheric pressure. This type of measurement is commonly used in various applications such as automotive tire pressure, HVAC systems, and other industrial processes where the influence of atmospheric pressure is not a primary concern.

• It is a gauge pressure, meaning it measures the difference between the internal pressure and the surrounding atmospheric pressure.
• It does not account for the atmospheric pressure itself.
• Widely used in day-to-day applications where the difference from atmospheric pressure is more relevant than the absolute pressure.

PSIA (Pounds per Square Inch Absolute), on the other hand, measures the total pressure, including the atmospheric pressure. This is crucial in scientific and engineering calculations where absolute pressure values are necessary for accuracy.

The atmospheric pressure at sea level is typically 14.7 PSI. Thus, PSIA is always higher than PSIG by the amount of atmospheric pressure. For instance, if you measure a vacuum in PSIA, it would show zero PSIA in a perfect vacuum (no atmospheric pressure), while a PSIG measurement would read -14.7 PSI under the same conditions.

• It is an absolute pressure, measuring the total pressure including the atmospheric pressure.
• Important in scientific and technical applications where precise pressure measurements are critical.
• Commonly used in calculations involving gas laws, thermodynamics, and fluid dynamics where the absolute pressure impacts the behavior of gasses and fluids.

Atmospheric pressure is the force exerted by the weight of the air above a given point on Earth’s surface. It is a crucial concept in both meteorology and various engineering applications.

Atmospheric pressure is the pressure exerted by the Earth’s atmosphere at any given point due to the weight of the air column above that point.

At sea level, the standard atmospheric pressure is approximately 101.3 kilopascals (kPa), 1 atmosphere (atm), or 14.7 pounds per square inch (PSI). This is often referred to as “standard atmospheric pressure.”

By understanding the distinction between PSIG and PSIA, you can ensure accurate pressure measurements and conversions, especially in contexts where the absolute pressure is critical for correct results.

The below calculator used to convert the PSIG(Pounds per Square Inch Gauge) to PSIA (Pounds per Square Inch Absolute)

Input: PSIG value (e.g., 50)

Output: PSIA value

Enter the PSIG value.

Click on the calculate button and the calculator adds the atmospheric pressure (14.7 PSI) to the entered PSIG value.

The resulting value is the pressure in PSIA.

To convert PSIG to PSIA, you need to account for the atmospheric pressure. At sea level, the typical atmospheric pressure is roughly 14.7 pounds per square inch (PSI).  The formula for conversion is:

PSIA=PSIG + Atmospheric Pressure (14.7 PSI)

To help you understand the conversion procedure, let’s look at an example:

• PSIG = 50 PSI
• Atmospheric Pressure = 14.7 PSI

PSIA=PSIG+Atmospheric Pressure

PSIA = 50+14.7

PSIA = 64.7

Therefore, 50 PSIG is equal to 64.7 PSIA.

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### Sundareswaran Iyalunaidu

With over 24 years of dedicated experience, I am a seasoned professional specializing in the commissioning, maintenance, and installation of Electrical, Instrumentation and Control systems. My expertise extends across a spectrum of industries, including Power stations, Oil and Gas, Aluminium, Utilities, Steel and Continuous process industries. Tweet me @sundareshinfohe