Light Emitting Diode
Current Limiting Resistor
Calculators

Single LED - LEDs in series - LEDs in parallel

Typical LED forward voltages:
 Red and Green LEDs: 2 volts
 Blue and White LEDs: 3.5 - 4 volts

Single LED



Single LED with single resistor
Supply Voltage
  Volts
Voltage Drop Across LED
  Volts
Desired LED Current
  milliAmps (mA)



Calculated Limiting Resistor
  Ohms
Nearest higher rated 10% resistor
 
Calculated Resistor Wattage
  Watts
Safe pick is a resistor with
power rating of
  Watts


LEDs in series



Several LEDs in series with one resistor
Supply Voltage
  Volts
Voltage Drop Across each LED
  Volts
Desired LED Current (per LED)
  milliAmps (mA)
How many LEDs connected
 



Calculated Limiting Resistor
  Ohms
Nearest higher rated 10% resistor
 
Calculated Resistor Wattage
  Watts
Safe pick is a resistor with
power rating of
  Watts


LEDs in parallel



Several LEDs connected parallel with one resistor
Supply Voltage
  Volts
Voltage Drop Across each LED
  Volts
Desired LED Current (per LED)
  milliAmps (mA)
How many LEDs connected
 



Calculated Limiting Resistor
  Ohms
Nearest higher rated 10% resistor
 
Calculated Resistor Wattage
  Watts
Safe pick is a resistor with
power rating of
  Watts