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

Recessed lights for a 12 × 28 ft home office with a 11 ft ceiling

Recessed lights needed
10lights
2 × 5 grid, about 6 ft apart in a 12 × 28 ft home office
Layoutacross the 12 ft dimension × along the 28 ft dimension2 × 5
Spacing (rule of thumb)half of the 11 ft ceiling5.5ft
Actual spacing to mark outafter rounding to whole fixtures6 × 5.6ft
First light from the wallhalf a spacing — closer washes the wall, further leaves dark corners3 × 2.8ft
Room area336ft²
Target light levelsustained close work40fc
Total lumens needed13,440lm
Lumens per fixtureabout 18 W each in LED1,344lm
Room width
12 ft
Room length
28 ft
Ceiling height
11 ft
Room
home office

The grid

Spacing for recessed cans is ceiling height divided by two. A 11 ft ceiling gives 5.5 ft, which across a 12 × 28 ft room works out to a 2 × 5 grid — 10 lights.

Rounding to whole fixtures moves the real spacing to 6 × 5.6 ft. Mark the ceiling off those numbers, not off the rule of thumb. The first row sits 3 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

336 ft² at 40 footcandles needs 13,440 lumens in the room, which is 1,344 lumens per fixture — around 18 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 5.5 ft here. Rounding to whole fixtures moves it to 6 × 5.6 ft — mark the ceiling off the real numbers, not the rule.
  • 1,344 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 this room wants 6″ cans, or more of them.
  • Home office is a task space. 40 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 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

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