What is the value of R when pressure is in ATM?

The value of the universal gas constant ( R ) when pressure is in atmospheres (ATM) is ( 0.0821 , \text{L} \cdot \text{ATM} / (\text{K} \cdot \text{mol}) ). This value is commonly used in the ideal gas law equation ( PV = nRT ), where ( P ) is pressure, ( V ) is volume, ( n ) is the number of moles, ( T ) is temperature in Kelvin, and ( R ) is the gas constant.