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Power Consumption of RGB LED Strips

This guide will help you in estimating the power consumption of your LED setup. I’ve tried to keep it as straight forward and simple as possible on the one hand, but on the other hand didn’t want to limit it to only specific strips. Thus, this guide will show you how you can calculate the minimum wattage requirements for your power supply for not just analog type RGB strips in three different package sizes, but for addressable WS2812b strips as well. For a better understanding I’ve also included a few examples.

SMB LED Modules

The variety of Surface Mounted Device (SMD) modules for LEDs is huge, where each module is distinguished by the geometrical dimension of the LED package. In this guide, we will discuss the most commonly used packages 3528, 5050 and 5630, which are summarized in the following table.

LED Package Dimensions Chip Surface Area Current per Channel Voltage Drop
3528 3.5 mm x 2.8 mm 9.8 mm² 7-10 mA 2.8 - 3.4 V
5050 5.0 mm x 5.0 mm 25 mm² 20 mA 2.8 - 3.4 V
5630 5.6 mm x 3.0 mm 16.8 mm² 50 mA 2.8 - 3.4 V

It can be observed, that the 5630 package has the highest power consumption. In general, a higher power consumption also leads to a higher lighting output intensity for LEDs. Thus, sorting the packages above considering their output brightness yields 3528 < 5050 < 5630. Note, that the current draw in the table above is given per channel. If you consider all three channels of an RGB LED, then you have to multiply the current draw by three. Also, note that the actual current draws can differ from manufacturer to manufacturer.

RGB Strips

Before we can calculate the power consumption of a given LED strip, we need to distinguish between addressable and non-addressable LED strips, because they do not only differ in the operating voltage, but also in the wiring of each LED. In comparison with non-addressable LED strips, the WS2812 or WS2812b LED strips allow to set the color of each LED on the strip individually.

Non-Addressable Strips

Analog type RGB LED strips mostly group three serial LEDs into one segment and arrange each segment electrically in parallel, resulting in an operating voltage of approximately 12 V. Because of this structure, each segment consumes a power of U_v \cdot I_{ch} per channel, where U_v = 12V is the operating voltage and I_{ch} represents a current draw from the table above. Let N be the number of segments of a given RGB LED strip, then its overall power consumption for all three channels can be calculated with

P = 3 \cdot N \cdot U_v \cdot I_{ch}.

If you want to calculate the power consumption for a single color LED strip, you can simply drop the multiplication by 3 in the previous formula.

Lets take a look at a two examples.

Example 1) 5m 5050 Strip with 150 RGB LEDs

In this first example, I want to show you two ways on how you can calculate the overall power consumption. The first approach will simply consider the amount of LEDs on the strip to calculate the power consumption. The second approach will show you, how you can calculate a power consumption on per-meter basis.

1a) We can derive the number of segments by dividing the amount of LEDs by 3, which yields N = 150 / 3 = 50 segments. With an operating voltage of U_v = 12V and a current draw per channel of I_{ch} = 20mA, the overall power consumption can be calculated with

P = 3 \cdot 50 \cdot 12V \cdot 20mA = 36W.

1b) To calculate the power consumption of the strip per meter, we have to derive the number of segments per meter beforehand. To achieve this, we simply divide the amount of LEDs by the length of the strip and get the number of LEDs per meter as 150 / 5 = 30. Further dividing by three yields N = 30 / 3 = 10 segments per meter. With this, the power consumption per meter can be calculated with 3 \cdot 10 \cdot 12V \cdot 20mA = 7.2W/m. Eventually, the consumption of the whole strip can be calculated by multiplying with its length, yielding

P = 7.2W/m \cdot 5m = 36W,

which agrees with our result in 1a).

The reason, why I wanted to demonstrate you the second approach, is because it is especially useful when considering the question, how much of the strip you are able to run with a given power supply.

Example 2) 5m 5630 Strip with 150 RGB LEDs

Analogously to the previous example, we first determine the number of segments by dividing the number of LEDs by 3, yielding N = 150 / 3 = 50 segments. With an operating voltage of U_v = 12V and a current draw per channel of I_{ch} = 50mA, the overall power consumption can be calculated with

P = 3 \cdot 50 \cdot 12V \cdot 50mA = 90W.

Addressable Strips (WS2812/WS2812b)

Unlike the segmentation method for analog type LED strips, where three LEDs are grouped into one segment, in addressable strips each LED has to be powered individually in order to allow each RGB LED to shine in its configured color. Further, in WS2812/WS2812b strips each RGB LED is packed with its own controller and all LEDs are aligned electrically parallel. On the one hand, this allows for a reduced operating voltage of U_v = 5V, but on the other hand such strips need a higher overall current compared to analog type RGB LED strips with similar power consumption.

All WS2812/WS2812b strips use 5050 RGB LED packages, which means, each RGB LED has a maximal current draw of I_{ch} = 20mA according to the table above. Like above, we are looking for the overall power consumption of a given strip at full brightness in white. Let’s consider such an addressable strip with N LEDs. Then its max. power consumption for all three channels can be calculated with

P = 3 \cdot N \cdot U_v \cdot I_{ch}.

Example 1) 5m WS2812b Strip with 150 RGB LEDs

With an operating voltage of U_v = 5V, a current draw of I_{ch} = 20mA per LED and per channel, and an amount of N = 150 LEDs, the max. power consumption of the strip can be calculated as

P = 3 \cdot 150 \cdot 5V \cdot 20mA = 45W.

Note, that the power supply has to be capable of delivering up to

I_{max} = 3 \cdot 150 \cdot 20mA = 9A.

Example 2) 5m WS2812b Strip with 240 RGB LEDs

In analogy to the previous example, the max. power consumption of this strip can be calculated by considering the different amount of N = 240 LEDs, yielding

P = 3 \cdot 240 \cdot 5V \cdot 20mA = 72W.

Note, that the power supply has to be capable of delivering up to

I_{max} = 3 \cdot 240\cdot 20mA = 14.4A.

Additional Tips

The following tips should help you on your journey through the LED world.

Power Supply

When choosing a proper power supply for your setup, it should be capable of providing at least the power consumption calculated with the formulas above, assuming that you want to be able to power your setup at full brightness for a long period of time. If your setup does not require this feature, then you could as well reduce the wattage your power supply has to provide. However, keep in mind that in this case your power supply will be overloaded every time you attempt to run your strips at full brightness. Many newer power supplies come with an over-current protection, so its generally not a big deal, but it can definitely reduces the lifetime of both, your supply and your strips.

Tip

Instead of installing one big power supply for your setup, think about driving the load with multiple power smaller supplies, each of them driving one segment of your setup.

Voltage Drop

If you experience a voltage drop on your RGB Strips due to its length (resulting in an loss in brightness of the RGB LEDs towards the end of the strip), or for RGB Strips longer than 5m, I recommend using RGB amplifiers after every 5m part to avoid such unwanted brightness gradients towards the end of the strips.

Passive/Active Cooling

Keep in mind, that generally the higher the power consumption in relation to the strips length is, the higher its temperature is going to get. If you observe, that your strips are getting too hot, try sticking them on a more thermoconductive material, like aluminum for example. This additional passive cooling through heat distribution is sufficient enough in most cases.

Warning

Also, please do not forget, that your power supply produces heat as well. Do not place the power supply in a closed box. Plan for heat outlets, and if required, active cooling.