LED Resistor Calculator
Calculate LED current-limiting resistor
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How to Use LED Resistor Calculator
Enter source voltage
Enter your power supply voltage.
Enter LED specs
Enter LED forward voltage and current.
Get resistor
See required resistor value and nearest standard.
Why Choose AllTools LED Resistor Calculator?
- ✓ Simple calculation
- ✓ Nearest standard value
- ✓ Power dissipation
- ✓ Common LED presets
- ✓ Series/parallel
- ✓ No data stored
Why Use This Tool
- ★ All calculations happen locally in your browser
- ★ Completely free with no usage limits
- ★ No account or registration required
- ★ Based on established scientific formulas and constants
- ★ Works on any device with a modern browser
Related Resources
Frequently Asked Questions
What are common LED values? ▼
Red: 1.8-2.2V/20mA. Green: 2.0-3.0V/20mA. Blue/White: 3.0-3.5V/20mA.
What if my LED has no datasheet? ▼
Use common defaults: red LEDs are typically 1.8-2.2V at 20mA, green 2.0-3.0V, and blue or white 3.0-3.5V at 20mA.
Does this work on mobile? ▼
Yes. All AllTools tools are fully responsive and work on phones and tablets.
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