Evenly spaced recessed lights give uniform light without dark patches. A common rule is to space them about half the ceiling height apart – 4 ft apart on an 8 ft ceiling – with the first row about half that distance from the walls.
How to use the Recessed Lighting Layout Calculator
- Room length
- Room width
- Ceiling height
- Rows of lights
- Columns of lights
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter the room length and width, the ceiling height, and the number of rows and columns of lights you want.
Tips
- Use the figures from your own bills and product labels – prices and appliance ratings vary widely.
- Look at yearly totals: small daily costs add up and make it easier to compare options.
- Round quantities up to whole packs, rolls or bulbs when you shop.
- Re-check the numbers when prices change; most results scale directly with the unit price.
Common mistakes to avoid
- Confusing watts (power) with watt-hours or kilowatt-hours (energy).
- Comparing prices without bringing them to the same unit first.
- Ignoring one-off costs such as installation, delivery or replacement parts.
Inputs explained
| Field | What to enter |
|---|---|
| Room length | Units: ft, m, in, cm, yd |
| Room width | Units: ft, m, in, cm, yd |
| Ceiling height | Units: ft, m, in, cm, yd |
| Rows of lights | A number |
| Columns of lights | A number |
What each result means
- Spacing between rows = [Room length]÷[Rows of lights]
- First row from wall = [Room length]÷(2×[Rows of lights])
- Spacing between columns = [Room width]÷[Columns of lights]
- First column from wall = [Room width]÷(2×[Columns of lights])
- Total lights = [Rows of lights]×[Columns of lights]
- Suggested lights (spacing = ceiling ÷ 2) = ceil([Room length]÷([Ceiling height]÷2) – 0.000001)×ceil([Room width]÷([Ceiling height]÷2) – 0.000001)
Example values
How the main result changes when Room length changes and everything else stays at the example values above:
| Room length (ft) | Spacing between rows (ft) |
|---|---|
| 8 | 2 |
| 12 | 3 |
| 16 | 4 |
| 20 | 5 |
| 24 | 6 |
| 32 | 8 |
Formula
Spacing between rows = room length ÷ rows; between columns = room width ÷ columnsDistance from wall = half the spacingRule of thumb: spacing ≈ ceiling height ÷ 2Worked example
Inputs — Room length: 16 ft; Room width: 12 ft; Ceiling height: 8 ft; Rows of lights: 4; Columns of lights: 3.
Results — Spacing between rows = 4 ft; First row from wall = 2 ft; Spacing between columns = 4 ft; First column from wall = 2 ft; Total lights = 12; Suggested lights (spacing = ceiling ÷ 2) = 12.
Frequently asked questions
How far apart should recessed lights be?
About half the ceiling height: 4 ft apart on 8 ft ceilings, 5 ft on 10 ft ceilings.
How far from the wall should recessed lights be?
About half the spacing between lights – typically 2–3 ft.
How many recessed lights for a 12 × 16 room?
With an 8 ft ceiling about 12 (4 rows × 3 columns).
What formula does the Recessed Lighting Layout Calculator use?
Spacing between rows = room length ÷ rows; between columns = room width ÷ columns.