Recessed Lighting Calculator
Enter your room size, ceiling height and room type to get how many recessed (can) lights you need, the ideal spacing between them, the distance from the walls, and a quick brightness check.
Recessed lights (also called can lights or downlights) look best when they're evenly spaced and sit the right distance from the walls. This calculator applies the industry spacing rule and a room-by-room brightness guide so you get a layout that's both even and bright enough for the job.
How to calculate recessed lighting spacing
The standard rule of thumb is to divide the ceiling height by two to get the spacing between fixtures. The first row of lights then sits half that distance from the wall, which keeps the cones of light overlapping so you avoid dark spots.
Distance from wall = Spacing ÷ 2
Lights per row = Room dimension ÷ Spacing (rounded)
| Variable | What it means | Typical value |
|---|---|---|
| Ceiling height | Floor-to-ceiling measurement | 8–10 ft (2.4–3.0 m) |
| Spacing | Centre-to-centre gap between fixtures | 4–5 ft (1.2–1.5 m) |
| Wall offset | Gap from the wall to the first row | 2–2.5 ft (0.6–0.75 m) |
Recommended spacing by ceiling height
| Ceiling height | Spacing between lights | Distance from wall |
|---|---|---|
| 8 ft (2.4 m) | 4 ft (1.2 m) | 2 ft (0.6 m) |
| 9 ft (2.7 m) | 4.5 ft (1.4 m) | 2.25 ft (0.7 m) |
| 10 ft (3.0 m) | 5 ft (1.5 m) | 2.5 ft (0.75 m) |
How many recessed lights do you need?
Spacing gives you an even grid, but brightness depends on the room. A good way to check is lumens per square foot: multiply your floor area by the target below, then divide by the output of each fixture (most LED downlights give 700–1,000 lumens; 800 is a safe planning figure). The calculator does this for you and flags whether your layout is bright enough.
| Room | Target brightness | Notes |
|---|---|---|
| Living room / bedroom | ~10–20 lumens / sq ft | Soft, ambient light |
| Dining room | ~30–40 lumens / sq ft | Pair with a central fixture |
| Kitchen | ~30–40 lumens / sq ft | Add task lights over counters |
| Bathroom | ~30–40 lumens / sq ft | Higher for vanity areas |
| Home office | ~40–50 lumens / sq ft | Brighter for detailed work |
Worked example
A 16 ft × 12 ft living room with an 8 ft ceiling:
| Spacing = 8 ÷ 2 | 4 ft between lights |
| Lights along length = 16 ÷ 4 | 4 |
| Lights along width = 12 ÷ 4 | 3 |
| Layout | 12 lights, 4 × 3 grid, 2 ft from each wall |
| Brightness check | 12 × 800 lm = 9,600 lm ≈ 50 lm/sq ft — plenty for a living room |
Prefer softer, more ambient lighting? You can use fewer lights (for example a 3 × 2 grid) and rely on dimmers — the spacing rule gives the brightest, most even result, not the only acceptable one.
Feet or metres?
Use the Feet / Metres toggle at the top of the calculator. Your inputs and all results convert automatically, so you get the same layout whether you plan in imperial or metric.