LED Series Resistor Calculator
An LED Series Resistor Calculator helps you determine the optimal resistor value needed to safely operate an LED with a given power supply voltage. LEDs require a current-limiting resistor to prevent excessive current flow, which can damage or destroy the LED.
How It Works
The required resistor value is calculated using Ohm’s Law: R=(Vsupply−Vforward)/Iforward
Where:
- R = Resistor Value (Ω)
- Vsupply = Supply Voltage (V)
- Vforward = LED Forward Voltage (V)
- Iforward = LED Forward Current (A)

Additionally, the power dissipated by the resistor is calculated as: P=I2×R
Where:
- P = Resistor Power (W)
Why Use a Resistor?
- Protects the LED from excessive current.
- Ensures consistent brightness and longer LED lifespan.
- Helps match different supply voltages to LED operating requirements.