Recessed Lighting Calculator

How to design a recessed lighting layout

Planning a recessed lighting (often called can lighting or pot lights) layout involves finding a balance between the quantity of light needed (lumens) and the physical symmetry of the fixtures (grid spacing).

Step 1: The Ceiling Height Spacing Rule

The standard rule of thumb is to base the distance between lights on your ceiling height:

• General Ambient Lighting: Divide the ceiling height by 2. (e.g. 8 ft ceiling = 4 ft spacing).
• Task/Accent Lighting: Divide the ceiling height by 3. (e.g. 9 ft ceiling = 3 ft spacing in kitchen work areas).

Step 2: Spacing from the Walls

To avoid casting shadows on the walls and creating a spotlight effect, the distance between the wall and the first row of fixtures should be exactly half the distance between the fixtures themselves.

Wall Distance = Center-to-Center Spacing ÷ 2

Step 3: Calculating Grid Counts

To fit the lights evenly into the dimensions of your room, divide the length and width of the room by the recommended spacing, and round to the nearest whole number. This gives you the number of columns and rows in your lighting grid:

Lights along Length = Round(Room Length ÷ Spacing)
Lights along Width = Round(Room Width ÷ Spacing)
Total Fixtures = Rows × Columns

Once you have the whole number counts, divide the actual length and width of the room by these numbers to find the exact center-to-center placement measurements.

Step 4: Checking Lumen Adequacy

Lumen output determines the brightness of the space. By multiplying the total number of fixtures by the lumen rating of your bulbs, you can check if your room meets recommended guidelines (typically 20-30 lm/sq ft for living rooms and 50-70 lm/sq ft for kitchens and bathrooms).