Calculate the required series resistor and power rating for your LED circuit.
Circuit Parameters
V
V
Resistor Values
Enter circuit details to calculate resistor
Quick Reference
V_sSource voltage
V_fLED forward voltage
I_fLED forward current
Overview
LEDs require a series resistor to limit current. This calculator determines the resistor value and power rating needed for your LED circuit using Ohm's Law.
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Pro Tips
R = (Vs - Vf) / If is the formula for calculating resistance.
Always choose a resistor with adequate power rating (P = I²R).
Standard LED current is typically 20mA for indicator LEDs.
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Fun Facts
"LEDs are diodes that emit light when current flows through them."
"Different LED colors have different forward voltages."
"High-power LEDs may require active current regulation instead of simple resistors."
