LED Resistor Calculator

Advanced LED resistor calculator offers tool for designing your LED circuits and selecting the optimal current-limiting resistor value. Simply fill in the necessary fields below and click “Calculate” to begin.

Unlike most online LED resistor calculators, this one offers user to specify custom resistor value or find alternative resistor values and calculate current (A) and power consumed (W) by LED diode and resistor.

LED Resistor Calculator

Enter your values on the left. The calculated resistor details and preview will appear on the right.

Example: 5V, 9V, 12V
Typical red LED: around 2V
Common LEDs often use 10–20mA
Number of LEDs in series
Leave empty to use the recommended resistor automatically.
Calculation Result
LED Color Typical Vf Voltage
Red 1.8 to 2.1 V
Amber 2.0 to 2.2 V
Orange 1.9 to 2.2 V
Yellow 1.9 to 2.2 V
Green 2.0 to 3.1 V
Blue 3.0 to 3.7 V
White 3.0 to 3.4 V
led-diode-diagram