Advertised watts are also referred to as LED watts. It’s theoretical watts. In theory, your LED bulb should be able to consume that much power if it is perfectly cooled. True wattage, on the other hand, represents how much power the grow light actually consumes from the supply.
In the actual world, LEDs are never run at their full rated wattage because the extreme heat produced by doing so causes LEDs to burn out and leads to color shift. This means that “Advertised Watts” is a completely meaningless number when comparing the amount of light output from two distinct lights. For instance, you may have two “500 LED Watt” lights, but one may run 200 watts of power while another may run 300 watts.
Since the “advertised watts” number is always higher and more impressive than the actual power consumption, many manufacturers who sell LED grow lights exclusively utilize it to advertise their products. However, this information is completely unrelated to the amount of wattage that is actually being used to create light.
When a grow light manufacturer doesn’t state how many actual watts the bulb uses, you can assume it’s operating at 60% of its theoretical watts.
