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LED Resistor Calculator

To calculate the resistor needed for a simple LED circuit, simply take the voltage drop away from the source voltage then apply Ohm's Law. In other words...

where:
• VS is the source voltage, measured in volts (V),
• VLED is the voltage drop across the LED, measured in volts (V),
• ILED is the current through the LED*, measured in Amperes (Amps/A), and
• R is the resistance, measured in Ohms (Î©).
* The current through the circuit is constant so ILED is also the current through the resistor.

This calculator is based on the Ohms Law Calculator, but takes into consideration the voltage drop from the LED. To use the calculator, enter any three known values and press "Calculate" to solve for the others.

Volts (V)

Volts (V)

Watts (W)

Click "Calculate" for the results.
The resistor wattage can be calculated using the following formula:

Watt = (Vs - VLED) x ILED

1. Can I use 1w led with 24E resistance directly in redimade RGB LED strip contoller.

1. what is the voltage output from the controller??

2. RGB Control Box
IR Remote Control
Input Voltage : DC 12 V
Output Current 6A (Max)
Model No. VR 24B

1. you can use the above software for calculating the exact resistance value...

according to me it's 29 ohms 3 watt

you can use this resistor and connect the LED with the controller output

3. Can I use 300 light smd strip & parrlar with 3 (1w) LED...?

4. I have 5W(5A) Ac COB LED. But when I connect it 220v it is getting over heated and not lasting. So how can I solve this problem??

1. which driver did you use? did you connect a heatsink with the LED??

2. It need not any Driver just need to connect directly to 220v. I have send a photo of it to ur email(admin@homemade-circuits.com) Please check it. Also it has ceramic board so it this need any heatsink???

3. I saw the image but I could not make out whether the LED has a driver or not....anyway if your LED is getting hot then definitely it needs a large heatsink for controlling the heat, and normally all high watt LEDs require heatsink otherwise they can get damaged within seconds.

4. This is new model of AC LED need not any Driver. U can search this in google to know abt it details. However I have used 5w heatsink panel with 4.7k resistor for stable the LED but brightness is reduced. Now suggest me any solution for proper brightness with LED stability.

5. All LEDs require a driver for operating, your module might be having in-built one.

anyway if heating is the issue then it can be solved only with a heatsink....you can check the datasheet of the module and learn how to attach the heatsink with it for ensuring its proper functioning.

remove the resistor it's not required.

6. Yes It has built in driver with micro parts. Also I am using 5w heat sink for my 5w AC LED. But the problem is:

1.when I am connecting it becomes overheat.
2.when I am using 4.7k resistor then it not heated but brightness is decreasing about 30%

Now have u any proper solution of brightness and over heat issue?

7. use a bigger heatsink, that's the only solution for the issue....or you can also incorporate a small fan for cooling the module.

5. Hi,

I want to use 12v 5w led with 12v 1 amp led driver, how much resistor value I need for that. Please suggest how to calculate, as in above calculator I can't use amp in source, only voltage.

1. Hi, to get current divide 5 by 12....

5/12 = 0.41 amps

6. no need to any resisitor