Series resistor
R = (V_supply − V_forward) / I. Choose the nearest standard value above the result and verify resistor power.
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LED Resistor Calculator
Choose a series resistor for an LED and check its power dissipation.
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Use the LED forward voltage and current from its datasheet, not a guessed value.
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Assumptions and limits.
- Single LED, DC supply and a chosen forward voltage/current from the LED datasheet.
Frequently asked questions
Can I connect LEDs in series?
Yes, if the supply exceeds the sum of forward voltages; one resistor can limit the string current.