LED Resistor Calculator
Use our free LED resistor calculator to find the perfect resistor for your LED circuit. Get accurate values for single LEDs, multiple LEDs, and different power sources.
Circuit Parameters
LED Presets
Learn More
To find the correct resistor, we use Ohm's Law. The goal is to limit the current flowing through the LED to its specified forward current (If).
R = (Vs - Vf_total) / If
- R is the resistance in Ohms (Ω).
- Vs is the total supply voltage.
- Vf_total is the total forward voltage of all LEDs in series.
- If is the LED's forward current in Amperes (A). We convert mA to A by dividing by 1000.
Supply Voltage (Vs): The voltage provided by your power source, like a battery or power adapter.
LED Forward Voltage (Vf): The amount of voltage the LED "uses up" or "drops" when it's on. This value is specific to each LED type and color and can be found in its datasheet.
LED Forward Current (If): The ideal amount of current the LED is designed to run at for optimal brightness and lifespan. Exceeding this can damage the LED.
Resistor: An electrical component that reduces current flow. We use it to protect the LED from receiving too much current from the power supply.
Results
Required Resistance
150 Ω
Recommended Standard Resistor (E24)
150 Ω
Required Power Rating
0.06 W
Resistor Color Code