What is the LED Resistor Calculator?
LEDs need a resistor to limit current or they burn out. Enter the supply voltage, the LED’s forward voltage (red ≈ 2 V, blue/white ≈ 3–3.3 V) and desired current (usually 10–20 mA), and how many LEDs are in series. You get the exact resistance, the next standard E12 value to buy and the power rating needed.
How to use the LED Resistor Calculator
- Enter supply voltage and number of LEDs in series.
- Enter LED forward voltage and current (mA).
- Buy the suggested standard resistor with the shown wattage.
Typical forward voltage
- Red / yellow: 1.8–2.2 V
- Green: 2.0–3.2 V
- Blue / white: 3.0–3.4 V
This LED Resistor Calculator is 100% free, needs no signup and runs privately in your browser – on phone, tablet or computer.
Last updated: · By NodifyTech