Recessed lights for a 20 × 30 ft kitchen with a 9 ft ceiling
| Layoutacross the 20 ft dimension × along the 30 ft dimension | 4 × 7 |
|---|---|
| Spacing (rule of thumb)half of the 9 ft ceiling | 4.5ft |
| Actual spacing to mark outafter rounding to whole fixtures | 5 × 4.3ft |
| First light from the wallhalf a spacing — closer washes the wall, further leaves dark corners | 2.5 × 2.1ft |
| Room area | 600ft² |
| Target light levelgeneral light — counters need task lighting on top | 35fc |
| Total lumens needed | 21,000lm |
| Lumens per fixtureabout 10 W each in LED | 750lm |
- Room width
- 20 ft
- Room length
- 30 ft
- Ceiling height
- 9 ft
- Room
- kitchen
The grid
Spacing for recessed cans is ceiling height divided by two. A 9 ft ceiling gives 4.5 ft, which across a 20 × 30 ft room works out to a 4 × 7 grid — 28 lights.
Rounding to whole fixtures moves the real spacing to 5 × 4.3 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
600 ft² at 35 footcandles needs 21,000 lumens in the room, which is 750 lumens per fixture — around 10 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 4 × 7 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 4.5 ft here. Rounding to whole fixtures moves it to 5 × 4.3 ft — mark the ceiling off the real numbers, not the rule.
- 750 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 either size covers it.
- Kitchen is a task space. 35 fc is the general level — countertops, desks and mirrors still need their own light. Ceiling cans alone put the light behind you and your own shadow onto the work.
- 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 4 × 7 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
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Read more
- 2700K vs 3000K: A Difference You Only See Side by SideShown separately, almost nobody can tell 2700K from 3000K. Shown together, everybody can. That single fact decides how you should buy them.
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- Bedroom Lumens: The Room Where Less Is the SpecificationThe bedroom is the only room where the target is a range you should deliberately sit at the bottom of, and where the dimmest setting matters more than the brightest.