Find the series resistor and power rating needed to drive an LED. This free tool by electronmagazine.com runs entirely in your browser — no sign-up, no uploads, no tracking of your input.
How to use
- Enter supply voltage.
- Enter LED forward voltage and current.
- Read the exact and nearest standard E12 resistor plus power rating.
FAQ
What forward voltage should I use?
Red ≈2.0 V, green ≈2.2 V, blue/white ≈3.0–3.3 V; check the datasheet.
Why pick a higher standard value?
Rounding up keeps current at or below the target.
What wattage resistor do I need?
Choose at least double the calculated dissipation.
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