Most UK bathrooms need four to six downlights. A small ensuite can manage on two or three, a large family bathroom or wet room might run to eight or nine. The starting point is room size, but ceiling height, room shape and how much other light you already have all move the final number, so treat any single figure as a sketch, not a spec.
Downlights are the bathroom's default choice for a reason. They are flush, unfussy, and they do not mind steam. But 'default' has bred a bad habit: fitting them in a straight, evenly spaced grid regardless of what is actually happening in the room underneath. A bath at one end and a shower at the other are not the same lighting job, and a grid treats them as if they are. Here is how to get the number and the layout right, and where the rules stop being rules.
The short answer, by bathroom size
Use this as your starting sketch. It assumes a standard 2.4m ceiling and a mix of LED downlights doing the general lighting, with no separate mirror or wall light yet added.
| Bathroom type | Typical floor area | Downlights | Notes |
|---|---|---|---|
| Small ensuite or cloakroom | Up to 3m² | 2 to 3 | Often better paired with a mirror light than lit by downlights alone. |
| Standard family bathroom | 4 to 6m² | 4 to 6 | The most common UK spec. Four in a simple square room, six if it is longer or has a separate shower enclosure. |
| Large bathroom | 7 to 10m² | 6 to 8 | Split across the bath, shower and vanity zones rather than one even grid across the whole ceiling. |
| Large bathroom or wet room with separate WC | 10m²+ | 8 to 9, or more | Treat it as two lit zones with their own switching, not one oversized grid. |
Notice the jump is not perfectly linear. A long thin bathroom and a square one of the same area do not want the same count, which is why the table is a starting point, and the next section is the part that does the real work.
The spacing rule of thumb (and why it is a guide, not gospel)
The rule electricians and lighting retailers commonly use is simple: divide your ceiling height in half, and that is roughly the distance to leave between downlights. Keep the first downlight in from each wall by about that same distance too, so the light reaches the edges of the room rather than stopping short. On a standard 2.4m ceiling, that gives you a spacing of around 1.2m between fittings.
We would not treat that as a fixed number, and neither should you. It is a starting sketch, not a wiring diagram. Room shape bends it: a narrow bathroom might take one row rather than a grid. Other light sources bend it too. Add a mirror or wall light and you can often drop a downlight without losing brightness where it matters. Personal preference bends it further. Some people want a bright, clinical wash for shaving. Others want the downlights doing quiet background work while a warmer fitting does the rest. There is no single correct number, only a correct number for your room.
Worked example: a 3m x 3m bathroom. That is 9m², roughly what a lot of people mean when they search for this by name. Run the spacing sum on a standard 2.4m ceiling: about 1.2m between fittings, and about 1.2m in from each wall. On a 3m wall that places one downlight in from each side with no room left for a third in that row, so a plain grid gives you four downlights in a 2x2 layout. That is the sketch, not the final answer for every 3x3 bathroom. At 9m² you are into the 'large bathroom' band in the table above, so if the room also holds a shower enclosure, or the ceiling runs taller than 2.4m, six across two zones is just as common in practice. The spacing sum tells you what a plain square room can take. The room's actual layout tells you whether a plain grid is what you actually want.
Where the IP rating changes the calculation
One thing the spacing sum will not tell you: any downlight directly above a bath or shower sits in what the wiring regulations call Zone 1, and it needs to be rated at least IPX4 (IP44) to go there. Downlights elsewhere in the room do not strictly need a wet rating, but most trade electricians spec IP44 throughout the whole bathroom anyway, because it is one less thing to get wrong and one less fitting to swap out later. For the full zone-by-zone breakdown, see our guide to bathroom lighting zones and IP ratings.
The mistake we see every week: downlights doing the whole job
Here is where we will happily overrule you. A bathroom lit entirely by a grid of downlights looks like a hospital corridor, not the boutique hotel bathroom everyone is actually trying for. Downlights are brilliant at general, even light. They are hopeless at flattering a face in the mirror, because the light comes straight down and throws a shadow under every feature you would rather it did not.
Fewer downlights and one proper mirror or wall light beat a bathroom stuffed wall to wall with recessed spots, every time. If your ceiling only stretches to six downlights, we would rather see four and a decent mirror light than six and nothing else. And the one thing we would never let you skip is a warm white (2700K to 3000K) rather than a cool daylight tone. Cool white at 11pm does not encourage anyone to relax, it encourages them to leave.
The short version
- Most bathrooms need four to six downlights; small ensuites two to three; large bathrooms or wet rooms eight or more.
- Space downlights roughly half the ceiling height apart, and keep the first one in from the wall by about the same distance.
- Treat that spacing sum as a guide. Room shape, other light sources and personal preference all move the final number.
- Anything directly above a bath or shower sits in Zone 1 and needs at least IP44 (IPX4).
- Downlights alone flatten a bathroom. Add a mirror or wall light and use warm white, not daylight.
For the full room-by-room plan, from zones to mirror lighting to the fittings themselves, start with our complete guide to bathroom lighting. When you are ready to choose fittings, browse recessed bathroom downlights or the wider bathroom lighting collection, all correctly IP rated for the room.
Frequently asked questions
How do I calculate how many downlights I need?
Start with your room size against the table above, then check it against the spacing rule: divide your ceiling height by two for the gap between fittings, and keep the first fitting in from each wall by roughly that same distance. Run the sum against your room's actual dimensions, not just its floor area, because a long thin bathroom and a square one of the same size want different layouts. Then adjust for what else is doing the lighting. A mirror or wall light often lets you drop a downlight without losing brightness where it matters.
How many downlights are in a 3x3 room?
On the plain spacing sum, four, laid out in a 2x2 grid. A 3m by 3m bathroom is 9m², which puts it into the 'large bathroom' band in our table above, so if the room also holds a shower enclosure or the ceiling runs taller than standard, six across two zones is just as common. See the worked example above for the full sum.
What is the rule of thumb for downlights?
Divide your ceiling height in half, and that is roughly the distance to leave between fittings. Keep the first downlight in from each wall by about that same distance too, so the light reaches the edges of the room. On a standard 2.4m ceiling that gives spacing of around 1.2m. Treat it as a starting sketch rather than a fixed number. Room shape, other light sources and personal preference all move the final count.
How far apart should downlights be from each other?
Around 1.2m on a standard 2.4m ceiling, using the half-ceiling-height rule, with the first fitting about 1.2m in from each wall. Taller ceilings widen that gap, lower ceilings tighten it. A row of evenly spaced downlights above a bath does a different job to the same number spread across a bath and a separate shower, so use the sum as a sketch and adjust for the room's actual layout.
Should I do 4 or 6 recessed lights in a bathroom?
Four suits a standard family bathroom of 4 to 6m², especially paired with a mirror or wall light. Six suits a larger bathroom, or one split across a bath, shower and vanity as distinct zones. If you are choosing between the two for the same room, we would rather see four downlights and a decent mirror light than six downlights and nothing else.
How many downlights do you need in a bathroom?
Most UK bathrooms need four to six. A small ensuite can manage on two or three, and a large bathroom or wet room can run to eight or nine. Room size is the starting point, but ceiling height, room shape and how much other light you already have all move the final number.
Words by Anne McKenna, KES Lighting & Home. Last updated 21 July 2026.
