1. What is an LED Resistor Calculator?

Definition: This calculator determines the proper resistor value needed to safely operate an LED with a given power supply.

Purpose: It helps electronics hobbyists and engineers prevent LED damage by limiting current flow through the LED.

2. How Does the Calculator Work?

The calculator uses Ohm's Law formula:

Where:

• \( R \) — Resistor value (ohms)
• \( V_{supply} \) — Power supply voltage (volts)
• \( V_{led} \) — LED forward voltage drop (volts)
• \( I_{led} \) — Desired LED current (amps)

Explanation: The resistor value is calculated by subtracting the LED voltage from the supply voltage, then dividing by the desired current.

3. Importance of Proper Resistor Selection

Details: Without proper current limiting, LEDs can burn out instantly or have reduced lifespan. This calculator ensures optimal brightness and longevity.

4. Using the Calculator

Tips: Enter the supply voltage, LED voltage (typically 1.8-3.3V), and desired current (usually 10-30mA). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What if my calculated resistor isn't a standard value?
A: Use the next higher standard resistor value for safety.

Q2: How do I know my LED's forward voltage?
A: Check the datasheet. Red LEDs are typically 1.8-2.2V, white/blue 3.0-3.6V.

Q3: What current should I use for my LED?
A: Standard LEDs: 20mA. High-power LEDs: check datasheet (may be 350mA+).

Q4: What about multiple LEDs?
A: For series: sum V_led values. For parallel: calculate each branch separately.

Q5: How do I calculate resistor power rating?
A: P = I² × R. Choose a resistor with at least double the calculated power.