LED Resistor Calculator

Calculate series resistor for LED based on supply voltage and desired current.

Supply Voltage (V) LED Forward Voltage (V) Desired LED Current (mA)

Result:

Enter values and click Calculate

Choose series resistor R = (Vs – Vf)/I to limit LED current. Resistor power dissipation P = I²R or (Vs-Vf)×I. Use margin and choose standard resistor value.