How Many Recessed Lights?

How many recessed lights?Determining how many recessed lights a room needs is one of the first steps when planning the lighting for a room.

Once you know how many lights are needed, you can decide on a layout and calculate their placement.

You can use the calculator to the right to get an idea of how many lights a room will need.

Before you get started, you’ll need to know two things; the room’s dimensions (length, width, ceiling height) and the beam angle of the light bulbs or LEDs that you’ll be using.

Some manufacturers do not list the beam angle on their packaging. They may just say flood or spot type. In that case you can use a default of 55-degrees for BR type flood lamps, and 45-degrees for PAR type flood lamps.

How to Measure a Large Room for Recessed Lighting

To calculate for general lighting, you’ll need to measure the length and width of the room or area. If you have a large room or an open floor plan, think of each living area within as a separate room.

In the example below, you can see a typical open floor plan that combines a kitchen, dining nook, and family room.
Reflected ceiling plan


Now take a look at the next example. Each area is defined for measuring and calculating the number of lights separately. The imaginary walls provide reference points to determine the size of each area and the number of lights needed.
Reflected ceiling plan with segments for lights



Recessed Lighting in Tall Ceilings

A common misconception is that tall ceilings require more lights, but that’s not always the case.
Tall ceilings allow the cones of light more distance to spread so they’ll easily provide coverage for the room.

Most often you’ll be better off installing brighter lights rather than more lights.

If the lights will be installed in a ceiling taller than 16-feet, you may also want to use PAR type light bulbs. They have a tighter beam control which will get more of the light down from the ceiling to the surface plane.

Once you know how many lights a room needs, you can use this placement calculator to create a reflected ceiling plan.





  1. Thank you for an awesome website. Very informative! I am about to get rid of my old florescent light in the kitchen (12ft x 9 ft) and install LED recessed lights. In attempting to figure out how many lights I need, I tried to use your calculator above but it kept returning “0” for the number of lights. Could you check if it’s “broken”? And additionally, would 1000 – 1100 lumen LED be bright enough for the kitchen of that size? Thank you for the advice.

    • Hey Kitan, I think you may be entering the dimensions in feet instead of inches. I tested it a few times using 108 x 144 and it seems to work fine. And yes, 1000 – 1100 lumen LEDs will be great in your kitchen. Send me a pic when you’re done I’d love to see it!

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