LED Resistor Calculator
Calculate the correct series resistor for any LED circuit. Enter your supply voltage, LED forward voltage, and desired current — get the exact resistance, nearest E12 standard value, and power rating.
Simulated — dashes show current flow, LED glow scales with forward current (red shown for ~2V Vf)
Red/Yellow ≈ 2.0V · Green/Blue/White ≈ 3.0–3.4V
Standard 5mm LEDs typically run at 20mA
Recommended resistor
150.00 Ω
- Exact calculated value
- 150.00 Ω
- Voltage across resistor
- 3.00 V
- Power dissipated
- 60.0 mW
- Suggested wattage rating
- 1/4 W
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