What are the common units of pressure? 

List them in order of smallest to largest unit.

1 Pa, 1 psi, 1 torr, 1 mm Hg, 1 in Hg, 1 atm:

Pascal (Pa)              101,325

kiloPascal (kPa)           101,325

Atmosphere (atm) 1 (exactly)

Millimeters of mercury (mmHg)    760

Inches of mercury (inHg)     29.92

Torr (torr)    760

Pounds per square inch (psi)      14.7

Answer: The order from the smallest unit to the largest is: Pascal, Torr, inches of mercury, psi, bar, and atmosphere.