💡 LED Resistor Calculator
Calculate the correct current-limiting resistor for your LED circuit. Includes presets for common LEDs and configuration options.
LED Specifications
Circuit Configuration
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Select an LED and configure your circuit to calculate the required resistor.
Understanding LED Current Limiting
Why Resistors? LEDs have very low resistance and will draw excessive current if connected directly to a power source, quickly burning out. A current-limiting resistor protects the LED.
Formula: R = (Vs - Vf) / I, where Vs is supply voltage, Vf is LED forward voltage, and I is desired current.
Series vs Parallel: In series, current is the same through all LEDs, but voltage adds up. In parallel, voltage is the same, but current multiplies. Each parallel branch should ideally have its own resistor.
Power Rating: Resistors dissipate power as heat. Always use a resistor with a wattage rating at least 2x the calculated power for safety and longevity.
Safety Tip: Never exceed an LED's maximum current rating. Running LEDs at 70-80% of max current provides optimal brightness and lifespan.
Disclaimer
This calculator is provided as-is for educational and informational purposes only. While we strive for accuracy, always verify calculations with professional standards and local electrical codes. Use at your own risk. For critical applications, consult a licensed professional electrician.
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