LED / Resistor CalculatorShow/Hide:DefinitionsFormulae Instructions
This page allows you to calculate the size/value or resistor required to run an LED with the correct current. The calculator will also work for two or more LED's in series, if you add up the voltage drop required for each LED.
Click on any of the links at the top of the page to reveal (or hide) more information about this calculator.
If you think that you can assist with this project in any way, then please visit the Support section and leave a message.
- Total Voltage drop across the LED and resistor
- Voltage drop rating, across the LED or LEDs in series
- Current rating of the LED / current through the finished system
- Value of Resistor required to limit the current
- Enter a value into each text-box in the form below.
- Choose appropriate unit-sizes for each value from each drop-down list.
- Hit the ENTER or RETURN key on your keyboard, or press the 'CalcResult' button below the input fields.
- A results area will appear at the bottom of the page, showing the required resistance value.
- Press the 'Clear Results' button if you wish to discard the current results list, otherwise further calculations will be added to the bottom of the current results list.