Use this tool to calculate the resistance required to drive one or more series-connected LEDs from a voltage source at a specified current level.

Note: When you select a resistor for this purpose, choose a device with a power rating between 2 and 10 times the value calculated below in order to avoid excessive resistor temperatures.

Formula

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

Formula

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