LED Series Resistor
A series resistor drops the supply voltage remaining after an LED's forward drop.
LED Series Resistor
Resistors · 3 inputs
How to use this calculator
- Enter supply voltage in V.
- Enter led forward voltage in V.
- Enter target current in mA.
- Select Calculate and keep the output unit with the answer.
Before you use the answer
Check the component connections and unit prefixes before copying a result into a circuit notebook. These tools describe ideal, introductory circuits. They do not replace datasheets, thermal checks, isolation requirements or qualified design work, and they are not intended for mains installation decisions.
Use a suitable standard resistor and verify the LED datasheet. This estimate assumes a fixed forward voltage.
Does it save my inputs?
No calculation history is stored by this website. The calculator works locally in your browser. See the privacy policy for hosting and contact details.
Why might a result be approximate?
Measurement uncertainty, ideal-model assumptions and floating-point rounding can all matter. Displaying more digits does not improve the original measurement.
Related calculations
LED Resistor Dissipation
The resistor dissipates the voltage it drops multiplied by the LED current.
Open calculator ↗Resistance Tolerance Span
Tolerance describes the permitted deviation from a nominal resistor value.
Open calculator ↗Capacitors in Parallel
Parallel capacitors share a voltage while their stored charges add.
Open calculator ↗