LED Resistor Calculator
Find the resistor needed to safely power an LED from any supply voltage.
V
V
mA
Typical: 20mA standard LED, 1–5mA low-current, 350mA–1A high-power.
LEDs
Resistor Required
Formulas
- R = (Vs − n×Vf) / If
- Vs = supply voltage, Vf = LED forward voltage
- n = number of LEDs in series, If = LED current (A)
- Power dissipated = (Vs − n×Vf) × If