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How to calculate power for led strip lights?

Many people do not know how to calculate the power based on the led strip, so there is no purpose when browsing the led power supply and don't know how to choose among the various power supply products.

An important principle for choosing an led power supply is whether the power is suitable for your LED strip lighting and led light controller. Actually, calculate the power that your LED light strip need is not a difficult thing.

There is a power calculation formula.

Total wattage = Wattage/meter x Length

When calculating the power of your led strip light, you need to follow the 80% principle. The power wattage you choose is 1.2 times more than the calculated theoretical wattage. This way your power supply will not overheat and affect its service life.


4 steps to calculate the power you need

Take our 24V waterproof RGB color changing led neon lights as an example.

Step 1. Know the wattage per meter of your led strip.

The LED light strip product details page will detail the various information required for the product. Here you can see the specific number of watts per meter of your light strip.

After entering the product page, slide down the page to find the product specifications, which indicate the working power, and find the power per meter.

And we can know that this 24V RGB color changing led neon consumes 8 watts per meter.


Step 2. Decide how long you want the length of your light strip.

Led strip lights are generally 5 meters in a roll, but there are also cases of one meter or two meters in length. Even high-voltage strip lights can reach 100 meters.

Decide the length of your light strip reasonably according to your project. It can be unpleasant to find that there is a shortage of light strips when installing your led lighting.

Our 24V RGB neon lights have options of 5 meters, 10 meters, 15 meters and 20 meters. If you do not find the right length for you, you can contact us and we provide customized services.


Step 3. Calculate the theoretical power according to the power formula.

Multiply the wattage per meter by the length of the strip light to get the total theoretical wattage of the strip. 

Theoretical power : 8w/m x 5m = 40W


Step 4. The 80% rule.

The actual required power is equal to the theoretical power multiplied by 1.2. That is, the power used by the strip light occupies 80% of the power supply.

Actual required power : 40W x 1.2 = 48W

Through calculation, we find that the 5m 24V RGB neon light actually needs a 48-watt power supply. And the longer the length, the more wattage required.

Not only our 24V RGB led neon rope lights, this calculation formula applies to any led strips. As long as you want to calculate the power of the power supply, you can use this formula.

Watt/meter Length Theoretical wattage Actual required wattage
8w/m 5m 40W 48W
8w/m 10m 80W 96W
8w/m 15m 120W 144W
8w/m 20m 160W 192W


Now, let's start to choose a suitable power supply for our 5m 24V led neon lights.

Find the led power supply drives in the categories. Click into the product category you are interested in, and find the power supply that matches the voltage and power. 

When choosing an LED power supply, it is required to know the characteristics of your light strip. For example, this led neon light is 24V, so we should choose 24V power supply. If you have waterproof requirements for the power supply, you should choose among the 24V waterproof power supply products. 

Among all 24V power supplies, there are 24V power adapters, 24V UL-Listed power supplies, and 24V waterproof power supplies. What is the difference?

The 24V power adapter carrying power is relatively small.

The 24V UL-Listed power supply has passed the UL certification, the quality is guaranteed, and has a five-year warranty. It provides IP20 non-waterproof and IP67 waterproof power supplies and Class II power adapters for you to choose.

The 24V waterproof power supply has more waterproof function than the ordinary power supply, and it is more secure for outdoor use.

• 24V power adapter: 12 / 24 / 48 / 72 / 96 / 120 W

• 24V UL-Listed IP20 power supply: 35 / 50 / 75 / 100 / 150 / 200 / 240 / 320 / 350 / 400 / 450 / 500 / 600 / 750 / 1000 W

• 24V UL-Listed IP67 power supply: 18 / 20.2 / 36 / 50 / 60 / 74.4 / 95 / 100.8 / 150 / 151.2 / 199.2 / 480 / 600 W

• 24V UL-Listed Class II power adapter: 6 / 15 / 18 / 25 / 36 / 40 / 60 / 90 / 120 / 160 / 221 / 280.08 W

• 24V waterproof power supply: 20 / 30 / 40 / 50 / 60 / 80 / 100 / 120 / 150 / 200 / 250 / 300 / 350 / 400 / 500 / 600 W

Therefore, a 5m 24V RGB led neon light with 48W should choose the 48W 24V power adapter, the 50W 24V UL-Listed IP20 power supply, the 50W 24V UL-Listed IP67 power supply, the 60W 24V UL-Listed Class II power adapter, or the 50W 24V waterproof power supply.

One thing to note is that when the power option does not have the same number as the actual required power you calculated, you need to choose a power that is a little larger than your number. 

For example, in the 24V UL-Listed IP20 power supply, there are no 48W power supply, it doesn’t matter to choose the 50W power supply.

If you need to install an led controller, the power required by the LED light controller is the same as the power required by the LED power supply, so the led neon light need a 48W LED controller.

*If you are looking for led controllers, you can read: How to choose led strip light controllers?



It is not difficult to calculate the power and choose the right power supply. Be patient and know more about it. You can do the job. If you have other questions, please feel free to contact us. 


*What you need to know about led light strip installation: 

How to cut led strip lights?

How to connect two light strips together?

How to wire single color led strip lights?

How to wire tunable white/CCT led strip lights?

How to wire RGB color changing led strip lights?

How to wire RGBW led strips?

How to wire RGBCCT led strip lights?

How to wire addressable led strips?

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