passive components

LED Series Resistor

Computes the required series resistor value for an LED circuit using: R = (Vs - Vd) / If, where Vs is the supply voltage, Vd is the LED forward voltage drop, and If is the LED forward current.

Inputs

Supply Voltage(V)

Supply voltage in volts

Voltage Drop(V)

LED forward voltage drop in volts (typically 1.8–3.3V depending on colour)

Forward Current

LED forward current value

Current Unit Multiplier

Unit multiplier for forward current — A: 1, mA: 1000

Results

⚠Forward current must be greater than zero

Resistance—ΩRequired series resistor value in ohms