LED Series Resistor Calculator

This tool calculates the precise resistance needed to protect an LED from overcurrent based on the supply voltage and the LED’s specific electrical characteristics.

Use this tool to:

  • Protect your components by ensuring the LED does not exceed its maximum rated forward current (typically 20mA for standard LEDs).
  • Select the correct resistor wattage to avoid overheating, especially in high-voltage circuits where the resistor must dissipate significant heat.
  • Determine brightness levels by adjusting the target current; lower current values will result in a dimmer LED and longer battery life.
Circuit Parameters
Calculated Resistor

*Formula: R = (Vsupply - Vf) / If. Ensure the supply voltage is greater than the LED forward voltage.

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