Yields! With a quality LED grow light and an average-to-good grow, you can expect yields of about 0.5 to 1g/watt.
The final yield depends a lot on strain and grow skill, as well as the quality of the lamp itself, but that’s a good rule of thumb for most models. For example, a 200W LED (200W true power draw, not an “equivalent” wattage) would yield about 100-200 grams on average, or 3.5 to 7 ounces.
Today’s LED models are much better for growing cannabis than the ones available even a few years ago. Many modern lamps are full spectrum or “wideband” spectrum (instead of only red and blue light diodes, which product a bluish purple light and are sometimes called “blurples”). Full spectrum light is easier on the eyes and adding at least some amount of green light to blurples typically results in healthier growth. Other spectrum colors like red, far red, and infrared are important for the budding/flowering stage. LED manufacturers have developed specialized lenses to point light directly to the plants and increase penetration, resulting in bigger yields for the same amount of light compared to older models. There are also many different form factors, with everything from the casing to the size of the diodes varying from model to model.
Modern LED grow lights can produce impressive results. These cannabis plants were grown completely under LED grow lights from seed to harvest!