Formulas used
- R = (Vsupply - n x Vf) / I
- Power = I squared x R
Frequently asked questions
Why round the resistor up?
A slightly larger resistor gives slightly less current, which keeps the LED safe. Rounding down can push it above its rating.
What current should I use?
Most indicator LEDs run well at 5 to 20 mA. Check the data sheet for the maximum.