1. What is an LED Resistor Calculator?

Definition: This calculator determines the appropriate resistor value needed to safely operate an LED in an electronic circuit.

Purpose: It helps electronics hobbyists and engineers select the correct current-limiting resistor to prevent LED damage.

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 drops the excess voltage (supply minus LED voltage) while limiting current to the desired value.

3. Importance of LED Current Limiting

Details: LEDs require precise current control. Too much current can burn out the LED, while too little makes it dim.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: What's a typical LED voltage drop?
A: Red LEDs ~1.8-2.2V, blue/white ~3.0-3.6V. Check your LED's datasheet for exact value.

Q2: How much current do LEDs need?
A: Standard LEDs typically 20mA, high-power LEDs may need more (check specifications).

Q3: What if my calculated resistor isn't a standard value?
A: Use the next higher standard resistor value for safety.

Q4: How do I calculate resistor power rating?
A: Power = (V_supply - V_led) × I_led. Choose a resistor rated for at least twice this value.

Q5: Can I connect multiple LEDs with one resistor?
A: Only if connected in series. For parallel LEDs, each needs its own resistor.