 When we use LEDs in circuits we always use a series resistor. We've made it even easier for you to calculate the value of this resistor with our LED calculator below. You can also watch this video where Kevin explains why we always use a series resistor, and explains how to calculate the value of the resistor.
LED type:
LED brightness (at typical current):
mCd
LED forward voltage:
V
Max LED current:
mA
Typical LED current:
mA
Battery voltage:
V
Number of parallel LEDs:
Calculated resistance:
Ohms
Preferred value:
Ohms
Resistor colour bands:

Instructions

1. Select an LED from the "LED type" drop down menu.
2. Click the "Get LED details" button.
3. If required, adjust the Typical LED current.
4. If using more than 1 LED in parallel, change the number of LEDs.
5. Enter the battery voltage.
6. Click the "Calculate resistor" button.

### Which Resistor Should I Use with my LED?

LED brightness is controlled using a current limit resistor to drop some of the battery voltage, calculate the resistance using the formulas in this guide. A worked example shows the calculation used to work out the resistance to accompany an LED in a typical circuit using a 9V battery. Mark Donnison

Hi Jerrard, it's always best to go with the manufacturer's guidance. If it says it requires a 3V supply, it is best to use a 3V supply. Jerrard

Hi i got a 3volt 1w led torch globe.. If i connect it to a 6volt battery… Will it burn out…. SURINDER MEHTA

Use 20 ea Diode Red LEDs approx 2v each, I want to make parallel design which running on 12v battery for my bike indicators. Pls suggest Resistance value.. Pls help SURINDER MEHTA

20 ea Diode Red LEDs approx 2v each, I want to make parallel design which running on 12v battery for my bike indicators. Pls suggest Resistance value.. Mark Donnison

Without knowing the specifications of the LEDs it is impossible to say. SURINDER MEHTA

Hi want to make parallel red led (20 LEDs) design which running on 12v bike battery. Pls suggest me exact resistor value and help to make correct circuit. Thank you Rob Haywood

Hi Ray, A single resistor for the amount of LEDs you entered in the calculator. Rob Ray Taylor

H, ref. resistor calculator, is it giving me the resistor per led or single resistor for how many leds in the circuit