LED Resistor Calculator
Adjust sliders to calculate resistor & power rating
9.0 V
2.0 V
20 mA
Source
Resistor
LED
Required Resistance
350 Ω
Power: 0.14 W (Nearest Standard: 390 Ω, 1/4W)
Safe Circuit Configuration
Key Features
- Interactive Range Sliders: Adjust source voltage, LED forward voltage, and forward current smoothly using intuitive sliders.
- Real-time Ohm’s Law Calculation: Dynamically computes required resistance ($R = \frac{V_S – V_F}{I_F}$) and power dissipation ($P = V \times I$) on the fly.
- Standard Resistor Recommendation: Suggests the nearest standard commercial resistor value (E24 series) and recommended wattage rating (e.g., 1/4W, 1/2W) for practical DIY component selection.
- Visual Circuit Feedback: Includes an interactive circuit graphic with an illuminated LED indicator that reflects system status.
How to Use
- Source Voltage ($V_S$): Drag the slider to set your power supply voltage (e.g., 5V, 9V, 12V).
- Forward Voltage ($V_F$): Adjust the slider to match your LED’s required operating voltage (typically 1.8V–3.3V depending on LED color).
- Forward Current ($I_F$): Set the desired operating current for the LED (typically 20 mA for standard indicator LEDs).
- Read Results: Instantly view the required resistance, nearest standard resistor size, and power rating displayed at the bottom card.