Recessed lights for a 10 × 30 ft bedroom with a 12 ft ceiling
| Layoutacross the 10 ft dimension × along the 30 ft dimension | 2 × 5 |
|---|---|
| Spacing (rule of thumb)half of the 12 ft ceiling | 6ft |
| Actual spacing to mark outafter rounding to whole fixtures | 5 × 6ft |
| First light from the wallhalf a spacing — closer washes the wall, further leaves dark corners | 2.5 × 3ft |
| Room area | 300ft² |
| Target light levellow ambient; reading needs its own lamp | 15fc |
| Total lumens needed | 4,500lm |
| Lumens per fixtureabout 6 W each in LED | 450lm |
- Room width
- 10 ft
- Room length
- 30 ft
- Ceiling height
- 12 ft
- Room
- bedroom
The grid
Spacing for recessed cans is ceiling height divided by two. A 12 ft ceiling gives 6 ft, which across a 10 × 30 ft room works out to a 2 × 5 grid — 10 lights.
Rounding to whole fixtures moves the real spacing to 5 × 6 ft. Mark the ceiling off those numbers, not off the rule of thumb. The first row sits 2.5 ft from the wall — half a spacing. Closer and you get a bright band down the wall; further and the corners go dark.
What to buy, not just how many
300 ft² at 15 footcandles needs 4,500 lumens in the room, which is 450 lumens per fixture — around 6 W in LED.
That is the number to shop by, and it is the one most layout calculators leave out. A 4″ LED downlight typically runs 600–800 lm; a 6″ runs 800–1,200 lm.
Before you cut
Find the joists first. A 2 × 5 grid rarely lands clear of framing on the first attempt, and shifting a can six inches to miss a joist is invisible once the trim is on. Put the whole layout on a dimmer while the wiring is open — it costs almost nothing then and cannot be added cheaply later.
Notes
- The spacing rule is ceiling height ÷ 2, which gives 6 ft here. Rounding to whole fixtures moves it to 5 × 6 ft — mark the ceiling off the real numbers, not the rule.
- 450 lumens per can is the figure to shop by. A 4″ LED downlight typically runs 600–800 lm and a 6″ runs 800–1,200 lm, so you could drop to 4″ cans or dim these down.
- 15 fc is an ambient level, which is what you want here. Recessed lights alone make a room look flat; the fix is lamps and wall light, not more cans.
- Put them on a dimmer. It costs almost nothing at install, and it is the difference between a ceiling that works at dinner and one that works at 11pm.
- Check the joists before marking. A 2 × 5 grid rarely lands clear of framing on the first try, and moving a can 6 inches to miss a joist is invisible once the trim is on.
Nearby sizes
- Recessed lights for a 8 × 30 ft bedroom with a 12 ft ceiling
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- Recessed lights for a 10 × 30 ft kitchen with a 12 ft ceiling
- Recessed lights for a 10 × 30 ft bathroom with a 12 ft ceiling
- Recessed lights for a 10 × 30 ft living room with a 12 ft ceiling
- Recessed lights for a 10 × 30 ft home office with a 12 ft ceiling
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