LED Resistor Calculator

Every LED needs something to limit its current.

Check the LED datasheet for its forward voltage and current. Everything is worked out in your browser. Nothing is saved or sent anywhere.

1. Supply

2. The LED

Red about 2V, white or blue about 3V.

3. Results

How it was worked out

    What this does and doesn't tell you

    • A 12V vehicle system can run at 14.4V or more while charging. Work out the resistor at the highest voltage it will see.
    • 240V AC mains can kill. In Australia, work on household mains wiring must be carried out by a licensed electrician. Low-voltage DC systems can still deliver very high current.
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