The LM317 regulator is a current regulating device, which produces a constant value of current regardless of source voltage or load resistance. A useful online calculator to calculate the resistance for the given input current in the LM317 regulator. This online LM317 current regulator calculator is used to calculate the resistor value from the given LM317 current or regulatory value of electrical circuit. In the below calculator enter the values for current in amps and submit.