Determining how many recessed lights a room needs is one of the first steps when planning the lighting for a room.
You can use the calculator on this page 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 and width) in inches. If you already know which lights you’ll be using, take note of the size and beam angle on the packaging.
If you haven’t chosen the recessed lights you’ll be using, you can experiment with the size and beam angles to see which combination would be ideal for the room.
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 setting of 110°-120° for BR LED Flood lamps or LED Modules.
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.
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.
Recessed Lighting in Tall Ceilings
A common misconception is that tall ceilings require more lights, but that’s not usually 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.