Resistor & LED Calculator

⚡ Single LED Resistor Calculator

Supply Voltage Vs (V)

LED Forward Voltage Vf (V)

Desired LED Current If (mA)

LED Colour (preset Vf)

Formula: R = (Vs − Vf) / If
Power in resistor: P = If² × R

💡 Multi-LED String Calculator

Calculate resistor for LEDs in series or parallel configurations.

Supply Voltage (V)

LED Forward Voltage (V)

LED Current (mA)

LEDs in Series

Parallel Strings

Config