LED Current Limiting Series Resistor Calculator
Arduino, Raspberry Pi, custom automotive lighting, DIY electronics projects. Calculates resistance value and minimum safe resistor power rating (Watts) to prevent burning out single or series LEDs.
Step-by-Step Derivation ▼ Show Steps
Calculations adhere to standard electrical engineering physics and National Electrical Code (NFPA 70) regulations.
Engineering Principles & Calculations
This calculator uses the exact mathematical relationships between Supply Voltage (V), LED Forward Voltage (V - presets for Red, Green, Blue, White), Forward Current (mA - default 20mA), Number of Series LEDs to determine Recommended Standard Resistor Value (Ω), Resistor Power Dissipation (W), Standard E12/E24 Value. In practical installations, factors such as ambient raceway temperature, harmonic distortion, duty cycle continuous operation, and conductor impedance must be accounted for by a certified electrician.
Calculates resistance value and minimum safe resistor power rating (Watts) to prevent burning out single or series LEDs.
Typical Application & Industry Guidelines
Arduino, Raspberry Pi, custom automotive lighting, DIY electronics projects.
LED Current Limiting Series Resistor Calculator Benchmark Lookup Table
| LED Color | Typical Forward Volts (Vf) | Nominal Current | Resistor for 5V Supply | Resistor for 12V Supply |
|---|---|---|---|---|
| Red | 1.8V - 2.1V | 20 mA | 150 Ohms | 560 Ohms |
| Green | 2.0V - 2.2V | 20 mA | 150 Ohms | 510 Ohms |
| Yellow / Amber | 2.0V - 2.1V | 20 mA | 150 Ohms | 510 Ohms |
| Blue | 3.0V - 3.4V | 20 mA | 100 Ohms | 470 Ohms |
| White | 3.0V - 3.3V | 20 mA | 100 Ohms | 470 Ohms |