LED Resistor Calculator
Series resistor for any LED.
Enter your values
Results update instantly as you type — no submit needed.
Results
- Resistor value
- 495 Ω
- Nearest E12 value
- 500 Ω
- Power dissipated
- 0.198 W
- Rating needed
- 0.25 W
Quick answer
The series resistor drops the difference between supply voltage and LED forward voltage.
R = (Vsupply − Vf) ÷ I
How to use the LED Resistor Calculator
- 1Enter the supply voltage.
- 2Enter LED forward voltage and desired current.
- 3Choose the next standard resistor above the result.
Frequently asked questions
What is typical Vf?
About 2 V for red, 3.2 V for blue and white.
Can I skip the resistor?
No — LEDs have no internal current limiting and will burn out.