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LED resistor

Calculate a series resistor and its power from the LED voltage and target current.

Ideal series-resistor estimate from supply, LED forward voltage and target current. Verify tolerances and resistor power rating.

DC supply voltage connected to the anode side of the resistor.

Forward voltage drop across the LED (from datasheet, typically 1.8–3.5 V).

Desired operating current for the LED (from datasheet, typically 10–20 mA).

Results

Enter supply voltage, Vf, and LED current, then calculate.

How this works

Ideal DC model; does not include dynamic resistance or temperature drift. Verify Vf from the LED datasheet at your operating current.

Related calculators

Check the stated method and limits against your installation. Results are calculation aids, not certification.

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Calculation model 2026-11-02.1