Lumens vs. Watts: How to Shop for LED Bulbs by Brightness

If you still buy light bulbs by asking for a "60-watt," you're not alone—but that habit is now leading shoppers astray. Watts and lumens measure two completely different things, and once you understand the difference, buying the perfect-brightness bulb becomes simple.

Watts Measure Energy, Lumens Measure Light

A watt is a unit of power—how much electricity a bulb consumes. A lumen is a unit of brightness—how much visible light the bulb actually produces. For a hundred years these two numbers rose together, so "60 watts" became shorthand for a certain brightness.

LEDs broke that link. Because they convert far more electricity into light and waste far less as heat, an LED can produce the same 800 lumens as an old 60-watt incandescent while drawing only 8–10 watts. Shopping by wattage now tells you almost nothing about how bright a bulb will be.

The Conversion Cheat Sheet

To replace an old incandescent, ignore its wattage and match its lumens instead:

• 40W incandescent ≈ 450 lumens
• 60W incandescent ≈ 800 lumens
• 75W incandescent ≈ 1,100 lumens
• 100W incandescent ≈ 1,600 lumens
• 150W incandescent ≈ 2,600 lumens

So if your lamp used to take a 60-watt bulb, look for an LED rated around 800 lumens—regardless of whether it draws 8, 9, or 10 watts to get there.

Efficacy: Getting More Light Per Watt

The ratio of lumens to watts is called efficacy (lumens per watt). It's the truest measure of how efficient a bulb is. A typical incandescent managed about 15 lm/W; modern LEDs routinely deliver 80–120 lm/W or more. Higher efficacy means lower electric bills for the same brightness, which is exactly why federal efficiency standards now require most general-service bulbs to clear 45 lm/W—a bar incandescent and halogen bulbs can't meet.

How Much Light Does a Room Need?

Lumens also help you light a whole room correctly. A rough rule of thumb:

• Living rooms & bedrooms: 10–20 lumens per square foot (softer, layered light).
• Kitchens & bathrooms: 30–40 lumens per square foot (brighter task light).
• Workshops & garages: 50+ lumens per square foot.

Multiply your room's square footage by the target, then divide across your fixtures. A 150-square-foot bedroom at 15 lm/sq ft needs roughly 2,250 lumens total—about three 800-lumen bulbs.

Don't Forget Color Temperature

Two bulbs can share the same lumen rating and still look completely different because of color temperature (measured in Kelvin). 2700K is warm and cozy; 5000K is bright daylight. Brightness and color are independent choices—pick your lumens first, then your Kelvin. Our Characteristics of Light guide walks through both.

Read the Lighting Facts Label

Every modern bulb package carries a "Lighting Facts" label, much like nutrition facts on food. It lists brightness in lumens, estimated yearly energy cost, life expectancy, light appearance (Kelvin), and energy used (watts). Glance at lumens and Kelvin first—those two numbers tell you almost everything about how the bulb will perform.

Shop Smart

The bottom line: buy the light you want (lumens), not the power you're used to (watts). Browse our LED bulb collection—every listing shows lumens and color temperature so you can match your old bulb exactly while slashing energy use. New to any of the terminology? The Batteries & Bulbs Glossary has you covered.