Lumens Per Watt: The Only Light Bulb Number That Matters

Watts tell you how much electricity a bulb eats. Lumens tell you how bright it actually is. Those are two different things, and American shelves have been selling you the wrong one for a decade.

Here’s the number almost nobody checks: lumens per watt.

The math takes 10 seconds in the aisle:

• 800 lumens ÷ 9W = 89 lm/W → fine
• 1,100 lumens ÷ 9W = 122 lm/W → this is the sweet spot
• 800 lumens ÷ 6W = 133 lm/W → excellent

Above 100 is good. Above 120 is future-proof.

Why it matters now: the federal minimum for general service lamps already sits at 45 lm/W — that’s the line that pushed incandescent and halogen bulbs off US shelves. Regulators have pointed toward 120 lm/W as the next target for general service lamps, with published analyses describing a 2028 timeline. Whatever happens with the rule, 120 lm/W is a good buying filter today.

Practical version: ignore the wattage, divide the two numbers on the box. If a cheap 4-pack doesn’t print lm/W anywhere, that’s your answer.