LED Resistor Calculator
Current-limiting resistor for any LED
📚 Learn more — how it works, FAQ & guide Click to expand
Learn more — how it works, FAQ & guide
Click to expand
LED resistor calculator
Calculate series current-limiting resistor for any LED.
How to use this tool
- 1
Enter source voltage
Battery or power supply voltage.
- 2
Enter LED specs
Forward voltage (Vf) and current (If) from datasheet.
- 3
See resistor
Exact + standard value, power rating.
Frequently Asked Questions
LED forward voltage typical
Red: 1.8-2.2V. Yellow/Green: 2.0-2.3V. Blue/White: 3.0-3.5V. UV: 3.3-4.0V. Always check datasheet.
Formula
R = (V_source - V_led) / I_led. Use LED current typically 10-20 mA. Power dissipation = (V_source - V_led) × I.
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