What makes this different
The calculator gives the exact resistor, nearest E12 standard value, resistor power dissipation, suggested wattage, and voltage headroom check.
LED Series Resistor Calculator
V
V
mA
series
LED resistor calculator with wattage and standard value guidance
Formula
Use R = (Vs - total Vf) / I. For LEDs in series, total forward voltage is the LED forward voltage multiplied by the number of LEDs.
Design tip
Use a resistor wattage at least 2x above calculated dissipation. This keeps the part cooler and improves reliability in enclosed projects.