💡 LED Resistor Calculator
Calculate the correct current-limiting resistor for your LED circuit. Supports single and series LED configurations.
Required Resistor
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Nearest Standard (E24)
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Power Dissipation
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Recommended Wattage
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Formula: R = (Vs − n×Vf) / If | P = If² × R
How to Use
- Enter your supply voltage (battery or power supply)
- Select LED color or enter custom forward voltage
- Set desired LED current (typically 10-20mA)
- Enter number of LEDs in series
- Use the calculated resistor value in your circuit