Recessed Lighting Layout Calculator
Enter a room's length and width and the largest spacing between recessed lights from your fixture's sheet, and get how many lights, the spacing each way and the distance from the walls; an L-shaped room is two rooms added together.
Estimates for planning, not professional advice. Read the full notice.
Example: a twelve by fourteen foot room
12 recessed lights
- Lights along the length 3 lights
- Lights across the width 4 lights
- Spacing along the length 4 ft
- Spacing across the width 3.5 ft
- Distance from the end walls 2 ft
Estimate for planning, from what you entered and the product data shown. Check product labels and your supplier before you buy.
Your project
Enter a size to see your total.
Each product is rounded up once for the whole project, so the total can be less than the items bought alone added together. A line counted from a cut layout (sheets, boards or tiles laid out piece by piece) is counted for each item and added.
Spacing and distance from the walls
These numbers follow the sizes above for every item in the list. The spacing is the largest one you typed; the layout shares each wall length equally.
Shopping list
| Item | Size | Buy |
|---|---|---|
| Recessed lights | recessed lights | 12 |
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Worked example: a twelve by fourteen foot room
Show the working
- Lights along the length: the length over the spacing, rounded up 12 ft ÷ 4 ft = 3 lights
- Lights across the width: the width over the spacing, rounded up 14 ft ÷ 4 ft = 4 lights
- Lights in all 3 × 4 = 12 recessed lights
Assumptions
The figures behind the example. Sourced figures link to their source below; a default is a starting value to check against your label or supplier.
| Assumption | Value | Details and changes |
|---|---|---|
| Distance from a wall, as a share of the spacing | 0.5 x spacing | |
| Default The layout puts the first light half a spacing from each wall. Check your fixture sheet for its own rule. | ||
Feet and inches, like 12' 6"
Lights by room size and spacing
Lights in all for five room sizes at three largest spacings
| Room | 4 ft apart | 4.8 ft apart | 6 ft apart |
|---|---|---|---|
| 10 by 10 ft | 9 lights | 9 lights | 4 lights |
| 12 by 12 ft | 9 lights | 9 lights | 4 lights |
| 12 by 14 ft | 12 lights | 9 lights | 6 lights |
| 14 by 16 ft | 16 lights | 12 lights | 9 lights |
| 16 by 20 ft | 20 lights | 20 lights | 12 lights |
Each cell is the lights along the length times the lights across the width. The spacings are examples; type the one from your fixture's sheet.
Questions
How many recessed lights do I need for a room?
Divide each room dimension by the largest spacing and round up, then multiply the two counts. The table lists room sizes at three spacings, and the calculator does it for yours.
What spacing do recessed lights take?
That comes from the fixture's sheet and your own plan, so the calculator asks you to type it rather than assuming one. Some rules multiply the ceiling height by a factor; multiply it out and type the result.
Why does the count change with the spacing?
Each wall length is divided into whole numbers of lights, so a small change in spacing can add a row. The table shows the count for three spacings side by side.