Welcome, Sunset. There are many variables that effect yield-light is just one of them. Trying to decipher what type of lighting you're using illustrates what difficulties most folks have trying to compare lights-false claims. Although led efficiency varies widely, using the actual power CONSUMPTION gets you in the ballpark. Compared to HID, most common led technology needs approx. 60-70% of the power consumption of HID to get the same amount of photons.