In Ideal Gas Law, there's  gas constant R that we need to use in the formula PV=nRT. There are times when we are given different units and we need to do conversioins and here are the proper units we use.

Since PV= nRT,

so R = PV/nT or we can say R equals  (pressure × volume) / (amount of gas × temperature).

We know that temperature can be in Celcuius , Fahrenheit and Kelvin.

For pressure we use units like atm, kPa and mmHg (torr).

For volumes, we may use cm³, m³, L or ft³.

Basically we just swap the units in the R formula, and get the gas constants with proper units. Most often we use these two gas constant units:

R=8.314 L kPa K⁻¹ mol⁻¹

R=0.08206 L·atm/mol·K

R = 62.36 L mmHg K⁻¹ mol⁻¹

R= 62.36 L torr K⁻¹  mol⁻¹