How many lumens do I need for my warehouse?

That depends entirely on what's happening on the floor. There's no one-size-fits-all number. Start by figuring out your target foot-candle level based on the work being done in each zone. General bulk storage needs only 5 to 10 foot-candles. Active forklift aisles and picking areas should hit 20 to 30 foot-candles. If you're doing packing, assembly, or scanning barcodes, bump that to 30 to 50. For fine inspection or quality control, you're looking at 50 to 100 foot-candles.

Once you have your target foot-candles, the rough math is simple: multiply your square footage by that number to get raw lumens. A 10.000 sq ft warehouse with a 30 fc target needs 300.000 raw lumens. But that's just the starting point. Ceiling height eats light fast. At 20 feet, a 20.000 lumen fixture works. At 40 feet, you need 40.000 lumens to get the same level on the floor. After you have the raw total, divide by the lumen output per fixture. For modern high bay LEDs (18.000 to 30.000 lumens is standard), you'll end up somewhere between 10 and 25 fixtures for a 10.000 sq ft space. If you have tall racking or dark walls, add 20% to account for light loss.