LED Current Draw Calculator

This tool calculates the current through a Light Emitting Diode (LED).

To calculate the current draw through an LED, you need to know the voltage supply (V), the forward voltage of the LED (Vf), and the value of the current-limiting resistor in the circuit. The current through the LED can be determined using Ohm’s Law.

Calculator

Enter these values in the calculator below

Formula

Vresistor​ = V​−Vf

I = Vresistor/R​​

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Example Calculation

Use the following numbers:

  • Supply Voltage (V) = 9V
  • Forward Voltage of the LED (Vf) = 2V
  • Resistor Value (R) = 330Ω

The current draw is 21 mA

(100 Pcs) MCIGICM 5mm LED Light Diodes, LED Circuit Assorted Kit for Science Project Experiment (Multi-Colored - 5 Color)

Important Considerations

  • Max Current Rating: Ensure the calculated current does not exceed the LED’s maximum current rating (typically 20-30 mA for most small LEDs).
  • Resistor Choice: Choosing the right resistor value is critical to ensuring the LED does not draw too much current, which could lead to overheating and damage.

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