LED Series Resistor Calculator
Calculate the required current-limiting series resistance and power dissipation to safely power an LED without burning it out.
Enter Supply Voltage, LED Voltage & Current
Recommended Resistor:
Required Resistance:
0.000 Ω
Nearest Standard (E24):
--
Resistor Power Dissipation:
0.000 W
Recommended Rating:
--
How to Use
- Enter your circuit's DC supply voltage (Vs).
- Enter the forward voltage drop (Vf) of the LED from its datasheet.
- Enter the desired forward current in mA (typically 15-20mA for indicator LEDs).
- Click CALCULATE to get the exact resistor value and wattage.
Core Formula
R = (Vs − Vf) / ILED
Power (P) = (Vs − Vf) × ILED
Typical LED Forward Voltages (Reference)
| LED Color | Typical Forward Voltage (Vf) | Typical Current |
|---|---|---|
| Red | 1.8V – 2.2V | 20 mA |
| Yellow / Amber | 2.0V – 2.2V | 20 mA |
| Green | 2.0V – 3.0V | 20 mA |
| Blue | 3.0V – 3.4V | 20 mA |
| White | 3.0V – 3.4V | 20 mA |
| Infrared (IR) | 1.2V – 1.6V | 20 – 50 mA |
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