LED Series Resistor Calculator
Estimate an ideal current-limiting resistance and its dissipation from entered LED parameters.
Your result
EVERYDAYEnter your values and select calculate.
On this page How it works & practical examples
How to use the LED Series Resistor Calculator
Enter forward voltage and target current from the component information for the intended operating point. Current is in milliamps and is converted to amps internally.
The calculation
Worked example
A 5 V source, one 2 V LED and a 20 mA target give 150 ohms and 0.06 W ideal resistor dissipation.
Assumptions and limits
Requires positive voltage headroom. It does not select a standard resistor rating or account for LED tolerances, thermal behavior or varying supply voltage; this is a nominal estimate.
Common questions
Which inputs should I use?
Enter forward voltage and target current from the component information for the intended operating point. Current is in milliamps and is converted to amps internally.
What does the result exclude?
Requires positive voltage headroom. It does not select a standard resistor rating or account for LED tolerances, thermal behavior or varying supply voltage; this is a nominal estimate.