The units of the universal gas constant R is derived from equation PV=nRT. It stands for Regnault. then R is in L⋅atm/mol⋅K. R has the value 0.082057 L⋅atm/mol⋅K with the above units for the remaining variables. In other scenarios with pressures of bars instead, you may also use 0.083145 L⋅bar/mol⋅K.