LED Series Resistor Calculator

About:

Use the calculator below to determine the series resistor needed to connect various series combinations of light emitting diodes or "LEDs". Use a resistor rated higher than the displayed power in the box below "Power (W)".

Choosing a resistor with twice the wattage rating is recommended to prevent it from getting hot.

Formula: R = (Vs - Vf) / If

Supply Voltage:
V
Forward Voltage:
V
Forward Current:
mA
Resistor Value:
Ω =
Power:
W =