The brightness isn't solely determined by wattage. It's about the PPFD (Photosynthetic Photon Flux Density), which measures the light available for photosynthesis. Our light has a PPFD that's 4-6 times higher than standard HID and HPS incandescent lights. That's why the 48-watt Sunvibe grow light seems brighter than a 240-watt incandescent bulb.