KelvinPlanHow much light each room needs, and what colour it should be.

Recessed lights for a 20 × 30 ft kitchen with a 11 ft ceiling

Recessed lights needed
20lights
4 × 5 grid, about 5 ft apart in a 20 × 30 ft kitchen
Layoutacross the 20 ft dimension × along the 30 ft dimension4 × 5
Spacing (rule of thumb)half of the 11 ft ceiling5.5ft
Actual spacing to mark outafter rounding to whole fixtures5 × 6ft
First light from the wallhalf a spacing — closer washes the wall, further leaves dark corners2.5 × 3ft
Room area600ft²
Target light levelgeneral light — counters need task lighting on top35fc
Total lumens needed21,000lm
Lumens per fixtureabout 14 W each in LED1,050lm
Room width
20 ft
Room length
30 ft
Ceiling height
11 ft
Room
kitchen

The grid

Spacing for recessed cans is ceiling height divided by two. A 11 ft ceiling gives 5.5 ft, which across a 20 × 30 ft room works out to a 4 × 5 grid — 20 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

600 ft² at 35 footcandles needs 21,000 lumens in the room, which is 1,050 lumens per fixture — around 14 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 × 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 5.5 ft here. Rounding to whole fixtures moves it to 5 × 6 ft — mark the ceiling off the real numbers, not the rule.
  • 1,050 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 × 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

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