What is the difference between psig and psia?

psig is measured relative to atmospheric pressure; psia includes atmospheric pressure. At sea level, psia = psig + 14.7.

How many psi is one bar?

One bar equals 14.5038 psi, so a 7 bar system runs at about 101.5 psig.

Absolute pressure. Using gauge pressure inflates the ratio and will make a healthy machine look overloaded.

Input unit

Value

PSI

125.00psi

Bar

8.618bar

Kilopascal

861.8kPa

Atmosphere

8.506atm

Absolute

139.70psia

psig + 14.7

Convert between psig, psia, bar, kPa and inches of mercury for compressed air work.

Enter the pressure value you measured.
Select the unit that value is expressed in.
Read the equivalent value in every other supported unit.
Confirm whether the reading is gauge or absolute before using it in a compression ratio.

What is the difference between psig and psia?: psig is measured relative to atmospheric pressure; psia includes atmospheric pressure. At sea level, psia = psig + 14.7.
How many psi is one bar?: One bar equals 14.5038 psi, so a 7 bar system runs at about 101.5 psig.
Which unit do compression ratio calculations need?: Absolute pressure. Using gauge pressure inflates the ratio and will make a healthy machine look overloaded.