π‘ LED Resistor Calculator
Circuit Parameters
Arduino: 5V/3.3V, USB: 5V, Battery: 1.5V/3V/9V
Red: 1.8-2.2V, Green: 2.0-3.0V, Blue/White: 3.0-3.4V
Standard LED: 20mA, High-brightness: 10-30mA
Multiple LEDs in series add their forward voltages
Required Resistance
-
Power Rating
-
Choose 2Γ for safety margin
LED Voltage Drop
-
Total forward voltage
π‘ How It Works
LEDs need a current-limiting resistor to prevent burnout. Ohm's Law: R = (Vsupply - VLED Γ N) / I
Typical LED Forward Voltages
- π΄ Red LED: 1.8-2.2V
- π’ Green LED: 2.0-3.0V
- π‘ Yellow LED: 1.8-2.2V
- π΅ Blue LED: 3.0-3.4V
- βͺ White LED: 3.0-3.4V
- π£ Infrared LED: 1.2-1.6V
Important Notes
- Choose a resistor with at least 2Γ the calculated power rating for safety
- If the result is negative, your supply voltage is too low β increase voltage or reduce LED count
- Standard resistor values: E12 series (common) and E24 series (precision)