A poorly lit room is a lot like a picnic in the rain! A thoughtful combination of well-distributed lighting from ceiling to mid-wall height brings your design to life. Recessed lighting or track lighting, chandeliers or pedant lighting (upper middle plane) floor and table lamps; accent or task lighting and wall sconces create adjustable wash and accent lighting where your you need it.

The output of light is measured in Lumens per watts (LPW). The recommendation for lighting per square foot varies by task, and guidelines vary by state. But let’s over-simplify and go with an average of between 15 – 35 Lumens of per square foot, depending on the home “zone” you’re lighting. It stands to reason that you need brighter task oriented lighting in work zones (kitchen, living, office) with more restful lighting levels in bedrooms.

So how much lighting is the right for your room?

To calculateLPW (below) use this basic guide:

Lumens ———————————————- (Lumens/Watts)

15 – Watt Incandescent————————————8

125 – 3 watt CFL——————————————-41

185 – 15 watt Krypton————————————–12

210 – 25 watt Incandescent———————————8

Ambient Lighting – 3-4 feet from Ceiling down

400 – 9 watt CFL—————————————— 44

460 – 40 watt incandescent——————————– 12

500 – 10 watt CFL—————————————– 50

General Room Lighting – Middle Height 3′-6′

890 – 60 watt Incandescent——————————–15

900 – 15 CFL———————————————–60

1180 – 75 watt Incandescent—————————— 16

1200 – 20 watt CFL—————————————-60

1380 – 23 watt CFL—————————————-60

Suitable For Tasks – directed at task; up to 30″

1750 100 watt Incandescent——————————-17

1750 29 watt CFL——————————————60

2780 39 watt CFL——————————————71

2780 watt Incandescent————————————19

General Lighting for this restful Bedroom retreat, we’ll calculate 15 Lumens per square foot. General Lighting (see chart) lights the middle 3′ of an average room with 9′ ceilings.

* 18′ x 17′ = 306 sf

* We’re recommending 15 Lumens per square foot for a more restful area.

* 306 square feet x 15 Lumens per sf is 4590 Lumen

* Divide 4590 by 1690 (1 average Incandescent Bulb)

* You need 2.92 Bulbs rounded up = 3 / 1690 Lumen (100 watt) incandescent bulbs

This being said, many light sources tend to “spill” light, meeting that a 100 watt incandescent bulb efficiently lights about 75% of our 15 – 35 lumens per square foot.

So the correct formula is:

Number of lumens – divided by the wattage x.25 (to compensate for Light spill) = NUMBER OF BULBS NEEDED.

To achieve Ambient Lighting (see the chart) let’s add dimmable recessed lighting or track lighting. A typical 4-inch fixture is spaced 4 feet apart (6″ fixtures about 6 feet apart). For the sake of discussion let’s use a 40 watt incandescent bulb from the chart.

* 306′ divided by 4′ (4″ recessed cans spaced 4′ apart)= 76.5 s.f.

* 76.5 s.f. divided by 40 (watts) = 5.1 bulbs (5 bulbs)

Now, If 5 bulbs efficiently light 75% of each square foot (due to light spill)

75% of 5 (use 5 fixtures x.25; it’s correct and easy) = 1.25, so you need 1 extra fixture:

Our Master needs: 6 40 watt recessed cans to get 15 LPW per square foot.

Now it’s time to decorate! This 306 sf Master Bedroom needs:

* 6 recessed dimmable recessed cans or 4 track lights

* 3 lamps with 3 100 watt bulbs, or 2 side 60 watt side table lamps and a 3 pendant light pendant chandelier with 40 watt bulbs will do, as it is mid-height.

Step back and have a look at your room now!