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

Recessed lights for a 16 × 20 ft garage with a 9 ft ceiling

Recessed lights needed
16lights
4 × 4 grid, about 4 ft apart in a 16 × 20 ft garage
Layoutacross the 16 ft dimension × along the 20 ft dimension4 × 4
Spacing (rule of thumb)half of the 9 ft ceiling4.5ft
Actual spacing to mark outafter rounding to whole fixtures4 × 5ft
First light from the wallhalf a spacing — closer washes the wall, further leaves dark corners2 × 2.5ft
Room area320ft²
Target light levelwork surface levels, not storage levels50fc
Total lumens needed16,000lm
Lumens per fixtureabout 13 W each in LED1,000lm
Room width
16 ft
Room length
20 ft
Ceiling height
9 ft
Room
garage

The grid

Spacing for recessed cans is ceiling height divided by two. A 9 ft ceiling gives 4.5 ft, which across a 16 × 20 ft room works out to a 4 × 4 grid — 16 lights.

Rounding to whole fixtures moves the real spacing to 4 × 5 ft. Mark the ceiling off those numbers, not off the rule of thumb. The first row sits 2 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

320 ft² at 50 footcandles needs 16,000 lumens in the room, which is 1,000 lumens per fixture — around 13 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 × 4 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 4 × 5 ft — mark the ceiling off the real numbers, not the rule.
  • 1,000 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.
  • Garage is a task space. 50 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 × 4 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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