Watt's Going On: Choosing the Correct Bulb by Converting Watts to Lumens

Watt's Going On: Choosing the Correct Bulb by Converting Watts to Lumens

Jason Yang
Aug 8, 2013

Buying light bulbs used to be much simpler: light fixtures were listed with a maximum wattage and buyers would simply purchase a corresponding bulb. Not anymore. Newer LED, CFL, and other energy efficient lighting have completely changed the values of wattage or eschew the ratings system entirely. Here's a handy guide to shine some light on how to choose the correct light bulb in this new age.

Traditionally household incandescent light bulbs were rated between 40 to 100 watts. In comparison, newer LED or CFL light bulb come equipped for as little as 5 to 15 watts. The American Lighting Association (ALA) explains quite simply why there's a discrepancy in how light bulbs are labeled for wattage:

The reason for this discrepancy is wattage tells you how much energy a bulb uses. And since the new LED and CFL light bulbs use much less energy, their wattage is much lower.

Therefore, labeling listed on older light fixtures no longer correspond directly with light bulb ratings for newer energy efficient bulbs. So, what's the correct way to match new bulb with lamps and fixtures today? Lumens.

Lumens are the metric for brightness, which offers a more applicable measurement to refer to by current standards. Here is a handy chart sourced from the ALA providing a direct comparison between the brightness of an LED or CFL light bulb compared to older incandescent bulbs.

The conversions listed above aren't exactly the easiest to commit to memory. Fortunately, manufacturers generally mark newer LED and CFL bulbs with wattage conversions on the front or back of packaging. Keep in mind though the conversion is correlated to the lumens output.

That's a lot of numbers, so we generally recommend thinking of 1,000 lumens as a baseline, equivalent to a traditional 60 watt bulb. Any higher or lower rating adjusts the brightness, so choose accordingly.

(Image; Vladimir Gjorgiev/Shutterstock; Chart: Gregory Han)

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