First off, it’s all about the lumens. Lumens are the visible light given off by a source, and they are the ultimate goal. Wattage has often been confused with lumens, thanks to how incandescent bulbs are rated (everyone knows that a 60W bulb is not as bright as a 100W one), but more efficient lighting technologies have greatly changed the relationship between wattage (essentially power usage) and lumens (light output). For example, an incandescent might operate at about 12-15 lumens-per-watt (lm/W), while an LED bulb will be in the range of 40-50, a much greater luminous efficacy.
