LED Lighting, More Useful Info

Buy Lumens, Not Watts

In the past, we bought light bulbs or tube light based on how much energy, or watts, they use. Wouldn't it make more sense to buy lights based on how much light they provide. When you're shopping for light bulbs, you can choose your next light bulb for the brightness you want by comparing lumens instead of watts. A lumen is a measure of the amount of brightness of a light bulb the higher the number of lumens, the brighter the light bulb.

“How many lumens do I need to light up my room?”

The answer will vary based on the design and colour scheme of your room, but here is good rule of thumb, loosely based on the IESNA Lighting Handbook:

Floors: 20 Lumens per Square Foot
Tables and Raised Surfaces: 30 Lumens per Square Foot
Desks and Task Lighting: 50 Lumens per Square Foot

For the average living room of 250 square feet, you’ll need 5,000 lumens as your primary light source (20 lumens x 250 square feet), equivalent to about five 100 watt incandescent light bulbs, or eight 10 watt LED light bulbs. Since you probably read on your couch, you’ll also need about 4 square feet of task lighting on each end of the couch. That’s 200 lumens each (50 lumens x 4 square feet), but you’ll need more if the light source is a lamp with a shade.

In your dining room, you’ll want about 30 lumens per square foot on your dining table (you want to see your food, but not examine it), so if your table is 6 x 3 feet, that’s 540 lumens.

Keep in mind, however, that these numbers are for typical conditions. If you have especially dark walls and furniture, you’ll need brighter light sources. The distance of your light source from the surface also changes the equation. We based our calculations on 8-foot ceilings and average height task lamps.