How to determine ceiling light size and hanging height for a room
Ceiling light width
A general rule of thumb formula can be used to determine an appropriate diameter for ceiling fixtures. To determine this, measure the length and width of the room. Add those two numbers together and then convert the total into inches. So if your room is 10 feet by 12 feet, the ceiling light should be 22 inches wide. If you are installing a ceiling light over a dining room table or kitchen island, you must measure the width of the table. Subtract 12 inches from the total width of the table or island to determine how wide your ceiling lights should be. To install two fixtures above the kitchen island or dining table, aim for each to be about 1/3 the width of the table or island below.
Ceiling light hanging height in an entryway or foyer
Keep 7 feet of clearance from the bottom of the ceiling light to the floor. In an open foyer or entryway, hang the ceiling light with the bottom at least 6″ higher than the door.
Ceiling light hanging height over a dining table
To avoid bumping heads, you should hang 30-36” from the top of your table if you have an 8’ceiling. For every foot of ceiling height beyond 8’, add 3-6” to the length of your chain/wire.
Ceiling light hanging height above the kitchen island
The general rule of thumb is to hang the ceiling lights 30-36 inches above the island surface. When hanging multiple ceiling lights above kitchen island, there is a general formula to get the number of minimal distance in between the ceiling lights: length of island in feet divided by the sum of ceiling light number and one. If you prefer bigger ceiling lights, go with even numbers using the same math above.
Ceiling light hanging height in bathrooms
Above the bathtub, keep 8 feet between the top of the tub and the bottom of the ceiling light. That can be a tall order for smaller bathrooms, so if the height doesn’t accommodate this rule, consider a smaller ceiling light or hang at least 3 feet away from directly over the tub (keeping the 7-foot clearance rule in mind).