LED Current Limiter

Series resistor pour LEDs; nearest E12/E24, dissipation

About this tool

Compute the series resistor for an LED string at a target forward current.

Method

R = (V_s − n · V_f) / I_f; resistor power P_R = V_R · I_f. Pick the rated wattage at 2× calculated.

Output

  • Calculated R plus the next-larger E12 and E24 standard values.
  • Resistor power, LED power, total draw, efficiency.
  • LED presets for common colors and a 1 W power LED.