How far apart to space recessed lights

Divide the ceiling height by two and space the cans that far apart. On an 8-foot ceiling that is 4 feet; on a 9-foot ceiling, 4.5; on a 10-foot ceiling, 5. PacLights, Cans and Fans and Govee all publish the same arithmetic, and Bees Lighting publishes it alongside an alternative - about two thirds of the ceiling height.

It is worth being precise about what this is. No standards body publishes it. It is guidance from lighting retailers and manufacturers, repeated because it produces reasonable results in ordinary rooms. Treat it as a starting grid you then adjust, not as a requirement you have to satisfy.

The reason it works is geometry: light from a ceiling fixture spreads as it falls, so a taller ceiling gives each fixture a wider footprint by the time it reaches the floor. Halving the height is a rough way of matching spacing to that spread. Beam angle changes it too, which is why beam angle and spread is worth reading before you commit to a grid.

The wall distance is the genuine dispute, and it is worth knowing rather than averaging away.

PacLights puts cans 2 to 3 feet from walls, and specifically 36 inches in kitchens. Cans and Fans agrees at 2 to 3 feet. Bees Lighting says the first row should be 12 to 18 inches from the wall - half the distance.

Both are defensible because they solve different problems. A can 12 to 18 inches out washes the wall, which is what you want above kitchen cabinets, a bookshelf or art. A can 2 to 3 feet out lights the floor and the room, which is what you want in a living room with nothing on the walls.

So the honest answer is: decide what the wall is for first. If it holds something you want lit, go closer. If it is a blank wall, go further and put the light where people stand.

Spacing tells you where they go. It does not tell you how many you need, and starting from a grid is how rooms end up over-lit and expensive.

Start with the room total. Multiply the floor area by 10 to 20 lumens per square foot for living spaces, then divide by what one fixture actually produces. PacLights, using a 20 lumens per square foot density and fixtures producing 600 to 1,000 lumens, puts a 200 square foot room at roughly 8 to 10 fixtures - and a 10 by 12 kitchen, at the much higher density kitchens need, at 12 to 15.

Then sanity-check the grid against the room. Six cans in a 12 by 14 living room is a reasonable ceiling. Twelve is a supermarket.

Canless is usually the retrofit answer. A slim canless fixture like the Sunco 6 in. or the Amico 6 in. needs only a hole and a junction box, which is what makes adding cans to a finished ceiling realistic. Both are selectable-CCT, so the color decision can wait until they are in.

If the cans already exist, this is a bulb job. An 850 lm BR30 in every can changes the room without changing the ceiling - the options are in the best BR30 LED bulbs.

Do not put a can directly over where you stand. A downlight above the sink, the hob or a desk chair lights the top of your head and casts your face into shadow. Offset it forward by a foot or two.

Keep the grid square to the room, not to the joists. Joists dictate what is easy; the eye notices what is crooked. If the two fight, move the light a few inches rather than accepting a visibly skewed row.