💡 LED Resistor Calculator

Find the correct current-limiting resistor for any LED circuit — single LEDs, series strings, and parallel arrays.

Single LED

R = (Vs − Vf) / If

Supply Voltage (Vs)

LED Colour Preset

Forward Voltage (Vf)

LED Current (If)

Series String

R = (Vs − n×Vf) / If

Supply (Vs)

LEDs in series (n)

Vf per LED

Current (If)

Parallel Array

R = (Vs − Vf) / (n × If)

Supply (Vs)

LEDs in parallel (n)

Vf per LED

Current per LED (If)

LED Quick Reference

Colour	Typical Vf	Typical If	Wavelength	Notes
Red	1.7–2.0 V	10–30 mA	620–750 nm	Most common; indicators
Orange	1.9–2.2 V	10–30 mA	590–620 nm	Indicators, displays
Yellow	2.0–2.2 V	10–30 mA	570–590 nm	Indicators
Green	2.0–3.5 V	10–30 mA	495–570 nm	Wide variation by type
Blue	2.5–3.5 V	10–30 mA	450–495 nm	Higher Vf than red/green
White	3.0–3.5 V	10–30 mA	—	Blue chip + phosphor
IR	1.2–1.7 V	20–100 mA	780–1000 nm	Remote controls, sensors

Tip: Never connect an LED directly to a voltage source without a resistor. The nearest E24 standard value is shown. Max continuous current for most 5mm LEDs is 20–30 mA.