If you’re working with LEDs, choosing the correct resistor is one of the most important steps to prevent burning out the LED and to get the brightness you want. Our free LED Resistor Calculator makes it easy to determine the proper resistor value using your supply voltage, LED forward voltage, and desired current.
Whether you’re building hobby electronics, repairing devices, working on automotive lighting, or experimenting with Arduino projects, this tool saves time and removes the guesswork.
How It Works
Simply enter:
- Supply Voltage (example: 5V, 9V, 12V)
- LED Forward Voltage (depends on LED color/type)
- Desired LED Current (mA)
The calculator instantly gives you:
- Required resistor value (Ohms)
- Nearest standard resistor size
- Power dissipation
- Recommended resistor wattage
Great For:
- DIY electronics projects
- Arduino and Raspberry Pi builds
- Automotive LED conversions
- Hobby circuit design
- Learning Ohm’s Law
- LED strip repairs and custom lighting
Why Use a Resistor with an LED?
LEDs require current limiting to operate safely. A resistor controls the current flowing through the LED, helping extend LED life and prevent failure.
Try the calculator below and get the right resistor value in seconds.
Click the picture to get to it…
