# LED Series Resistor Calculator

These calculators give values for LED current
limiting series resistors. The first calculator gives values based on standard LED types.
This should only be used if the LED forward voltage and current are not known. The second
calculator gives a more accurate value using these figures, which can be found in the
suppliers catalogue. Preferred resistor values are also calculated;
use the radio buttons on each calculator to select the preferred value series to use.

#### Calculate Resistor Value for Common LED Types:

#### Calculate Resistor Value from Vf and If:

#### Formula:

R = (V

_{s} - V

_{f}) / I

_{f}
= (Supply Voltage - Forward Voltage) / Forward Current

I

_{f} is in units of Amps,

__NOT__ Milliamps! (20mA = 0.02A)

For more details see the technical data section

here.

# If you found this calulator useful you should try Electronics Assistant!

- All the online calculators and more in a stand-alone application
- Converts Resistor & Inductor colour codes, calculates LED series resistors, capacitance
units, series / parallel resistors & capacitors, frequency, reactance & more
- Calculation of nearest preferred resistor values with a choice of 5 series from E12 to E192
- Print & save calculation results