Skip to content
Runs privately in your browser

Free Online LED Series Resistor Calculator

Estimate series resistance and resistor dissipation from supply, forward voltage and current in milliamps.

Your input stays on this device. Processing is bounded; regex runs in a worker with a two-second timeout.

Result



How to use LED Series Resistor Calculator
Estimate series resistance and resistor dissipation from supply, forward voltage and current in milliamps.
  1. Set Supply.
  2. Set Forward Voltage.
  3. Set Current Ma.
  4. Run the tool, review the result and its stated limitations, then copy or download if needed.
Example & practical use
Estimate series resistance and resistor dissipation from supply, forward voltage and current in milliamps. The example below demonstrates Supply; Forward Voltage; Current Ma.
Example input:
{
  "supply": 5,
  "forwardVoltage": 2,
  "currentMa": 20
}
Expected result (relevant fields):
{
  "ohms": 150,
  "watts": 0.06
}
Features & result limitations
Estimate series resistance and resistor dissipation from supply, forward voltage and current in milliamps.
Frequently asked questions
What inputs does LED Series Resistor Calculator accept?
Supply; Forward Voltage; Current Ma
How should I interpret the LED Series Resistor Calculator result?
Estimate series resistance and resistor dissipation from supply, forward voltage and current in milliamps.
Where does LED Series Resistor Calculator process my data?
Inputs are processed locally in your browser. Submitted text is not sent to external services. A successful-run event increments an aggregate tool counter without your input.