How to Convert PSI to PSIG

The unit psig takes its name from physical pressure gauges.
••• Jupiterimages/ Images

In general, pressure is a force acting on a surface area; the psi unit measures pressure as pounds of force and square inches of area. Absolute pressure, which is what "psi" usually represents, takes into account the atmospheric pressure that acts on most objects. But pounds per square inch gauge (psig) is typically the pressure difference between a supply tank and the outside air; it ignores atmospheric pressure. To convert psi to psig, you add atmospheric pressure to the psig value. Atmospheric pressure is 101,325 pascals, or 101,325 newtons per square meter.

    Divide 101,325 by 1,550, which is the number of square inches in a square meter: 101,325 ÷ 1,550 = 65.37. This is atmospheric pressure in newtons per square inch.

    Divide the answer from the previous step by 4.448, which converts newtons to pounds: 65.37 ÷ 4.448 = 14.696. This is atmospheric pressure, measured in pounds per square inch.

    Subtract this answer from your pressure. For example, if you are converting a pressure of 50 psi, then 50 - 14.696 = 35.3. This is the pressure measured in psig.

Related Articles

How to Convert mm Hg to in Hg
How to Convert Kilopascals to Joules
How to Convert mmHg to a kPa
What Is a Pascal Unit?
How to Convert Pounds Per Square Foot to PSI
How to Convert hPa to Altitude
How to Convert MPa to N/mm^2
How Do Piezoresistive Pressure Sensors Work?
How to Convert ATM Pressure to Celsius
How to Find the Cross Sectional Area of a Pipe
How to Calculate mmHg
How to Find Relative Barometric Pressure
Test Your Knowledge on Middle School Science
How to Calculate the Mass of a Moving Object
How to Convert PSIG to PSIA
How to Find Partial Pressures
How to Convert an Area to Square Feet
How to Type a Mixed Fraction in a TI-83 Plus
How to Write the Remainder As a Whole Number

Dont Go!

We Have More Great Sciencing Articles!