How much light for my tent?

Light is measured in PPFD (µmol/m²/s) at canopy level, not in watts. But for choosing a fixture, wattage per square foot is a reliable shortcut.

Wall watts vs. marketing watts

compare the fixture's power draw at the plug; ignore "equivalent" numbers.

most LED bars sit 12–24" above the canopy; a dimmable driver lets one fixture serve seedlings and mature plants.

a 4×4 fixture lights a 4×4 tent evenly; stretching it over 4×8 leaves dim corners. Two smaller fixtures beat one large one in a long tent.

plan ventilation together with lighting; see the inline fan guide.

Need help sizing?