LED Resistor Calculator
NEWCalculate the required current-limiting resistor value and recommended wattage rating for your LED circuits.
How to use LED Resistor Calculator
- Enter your Source Voltage (e.g. 12V or 5V).
- Select your LED color/forward voltage from the presets or enter a custom voltage.
- Enter the target LED current in milliamperes (typically 20mA).
- Enter the number of series LEDs, then click Calculate.
What is LED Resistor Calculator?
LEDs (Light Emitting Diodes) require a current-limiting resistor in series to prevent them from burning out when connected to a voltage source. This calculator determines the precise resistance value, power dissipation, and recommended standard resistor wattage rating.
FAQ
- Why do LEDs need resistors?
- LEDs are semiconductor devices that have very low resistance once their forward voltage threshold is exceeded. Without a resistor to limit the current, the LED will draw excess current and destroy itself.
- What is the standard resistor power rating?
- Resistors come in standard wattage ratings such as 1/4W (0.25W), 1/2W (0.5W), 1W, and 2W. You should choose a resistor rating that is at least twice the calculated power dissipation for safety.
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