Downlight Spacing Calculator & Free Layout Tool
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Mike's quick answer
With a standard 2.4 m ceiling, space kitchen downlights about 1.2 to 1.5 m apart (bathrooms 1 to 1.2 m), with the first light about half that from the wall, usually 0.6 to 0.75 m. Using 500 to 600 lumen fittings about 1.2 m apart, a 3 × 3 m kitchen needs four to six and a 4 × 4 m kitchen six to nine. Living rooms can go wider: about four for 4 × 4 m and six for 5 × 4 m. The calculator below fits the grid to your room.
Enter your room size, ceiling height and the lumens of the downlights you’re looking at, and the calculator lays out an evenly spaced grid, estimates how bright the room will be and gives you a file of positions for your electrician.
It works for any room. Kitchens need the most light and bedrooms the least, and the room presets set a sensible brightness target for each.
How to use the calculator
- Pick the room type. Kitchen (300), Bathroom (300), Living Room (150), Bedroom (100), Hallway (100) or Custom. The tool labels these presets in lux, but treat them as lumens per m² planning figures: the total output of all the fittings divided by the floor area. The preset sets the target for you. If you move the target brightness slider yourself, the tool switches to Custom.
- Set the room size. Length and width in metres, measured wall to wall, and the ceiling height. For an L-shaped room, work out each rectangle separately.
- Set the lights. Enter the lumens per fitting from the box or spec sheet (most home downlights give 350 to 700 lm), the beam angle, and the wall offset, which is how far the first row sits from the wall. Set it to about half your spacing, usually 0.6 to 0.75 m, or about 0.6 m along a kitchen wall with worktops.
- Check the layout. The top view shows each light and its beam; the 3D view can be rotated and zoomed. The summary gives the number of lights, the grid, an estimated brightness (labelled lux, and generous, as explained below), the beam spread at floor level and a verdict from “Too dim” to “Too bright”.
- Download the CSV. It lists every light with its X and Y position in metres, measured from one corner of the room, plus its row and column.
If the verdict says too dim, choose brighter fittings or tighten the grid. Under Advanced, a lower spacing factor puts the lights closer together; Auto-adjust sets the spacing for you from your target and lumens. Either way, check the verdict again afterwards.
Spacing rules that work
The calculator spaces lights at the ceiling height multiplied by a spacing factor. The default factor of 0.5 gives 1.2 m between lights on a 2.4 m ceiling, and you can set anything from 0.3 to 0.8. A tighter grid, 0.5 to about 0.6 (1.2 to 1.5 m apart), gives the even light you want in kitchens; bathrooms go a little tighter, 1 to 1.2 m, because the walls are close. A wider one, up to 0.8 (about 1.9 m on a 2.4 m ceiling), suits living rooms and bedrooms, where pools of light and a few lamps feel more relaxed.
On an open wall, keep the first light about half the spacing from the wall, usually 0.6 to 0.75 m, so the spacing looks even from the edge of the room inwards. Too close and the beams hit the wall as hard curved shadows, called scallops, which show up badly on textured walls. Too far and the edges of the room go dark.
In a kitchen, a line about 60 cm out from the worktop wall puts each light just in front of the wall units, which are usually 30 to 35 cm deep, so the beam lands on the front of the worktop rather than on the cabinet doors. The kitchen downlight spacing guide shows layouts for galley, L-shaped and island kitchens.
Beam angle and spread
Beam angle is how wide the cone of light is. The calculator’s beam spread figure shows how wide each pool is at floor level, and from a 2.4 m ceiling the difference is large:
| Narrow (24–36°) | Medium (40–60°) | Wide (60–90°) | |
|---|---|---|---|
| Pool at floor level | About 1.0–1.6 m | About 1.7–2.8 m | About 2.8–4.8 m |
| What it looks like | Defined pools, darker gaps | Even light, some overlap | Soft, even wash |
| Best for | Accent light, islands, worktop spots | Kitchens, bathrooms, most rooms | Living rooms and bedrooms |
At worktop height, about 1.5 m below the ceiling, each pool is a bit over a third smaller. That’s why kitchens need the tighter grid.
For general light in kitchens and bathrooms, use 50 to 60 degrees, with 36 to 40 degrees for focused light over a worktop or island. Use the same beam angle for every fitting in the grid, or the pools won’t match.
How many downlights do you need?
The calculator gives you an exact number, but these are typical figures for kitchens and bathrooms, using 500 to 600 lumen downlights about 1.2 m apart.
| Kitchen or bathroom downlights (500–600 lm, about 1.2 m apart) | |
|---|---|
| 3 × 3 m | 4–6 |
| 4 × 4 m | 6–9 |
| 5 × 4 m | 8–12 |
| 6 × 4 m | 10–15 |
Living rooms and bedrooms can be spaced wider, 1.5 to 2 m apart, with lamps doing the rest: about four downlights in a 4 × 4 m living room and six in a 5 × 4 m one. Living room downlights has the layouts. Brighter fittings of 700 lm or more mean you need fewer; 350 to 400 lm fittings mean you need more. The lumens guide explains how much light each room needs.
Bear in mind the estimate is generous. It divides the total lumens by the floor area and doesn’t allow for light absorbed by walls, units and dark floors, so the real level on a worktop will be lower. In a kitchen, plan under-cabinet lighting as well, and put the downlights on a dimmer so you can fit slightly more than you need and turn them down.
Choosing the downlights
Brightness
400 to 600 lumens per fitting suits general room lighting. Go for 600 to 800 in kitchens or under ceilings higher than 2.7 m.
Colour temperature
3000K warm white suits most kitchens and living areas. 2700K is cosier for bedrooms and living rooms, and 4000K gives crisper light for bathrooms and utility rooms. Use the same in every fitting in a room. The colour temperature selector lets you compare them.
CRI
This is how true colours look under the light. Choose CRI 90 or above for kitchens and bathrooms, where you want food and skin to look natural.
Fire rating and insulation
Downlights cut into a ceiling with a room above should be fire-rated under Approved Document B. If insulation will sit on top, as in a top-floor ceiling, choose fittings rated to be covered by it (often marked IC), so you don’t have to cut the insulation back.
IP rating
Kitchens and living rooms need no special rating. In bathrooms, BS 7671 asks for at least IPX4 in zone 1 (above the bath or shower, up to 2.25 m from the floor) and zone 2 (0.6 m beyond it), and most people fit IP65 over a shower. The bathroom zones guide has the diagram.
Dimming
Choose dimmable downlights and a trailing-edge LED dimmer such as the Varilight V-Pro, and check the dimmer’s minimum load against the number of lights. If you’re deciding between bulb and built-in LED, GU10 or integrated downlights compares the two.
Room-by-room settings
| Target (lumens per m²) | Beam angle | Colour temperature | |
|---|---|---|---|
| Kitchen | 300 | 40–60° | 3000K |
| Bathroom | 300 | 50–60° | 3000–4000K |
| Living room | 150 | 60–90° | 2700–3000K |
| Bedroom | 100 | 60° or wider | 2700K |
| Hallway | 100 | 60° | 3000K |
For how many downlights go in each room and exactly where, with plans for the main rooms, see the room-by-room downlight layout guide.
Kitchen
Put the lights over the worktops, not down the middle of the room, and add under-cabinet lighting so you’re not working in your own shadow. If there’s a dining area, put it on a separate circuit.
Bathroom
Use IP65 fittings over the shower. Light the face at the mirror from the front, with a mirror light or wall lights, rather than relying on a downlight directly overhead, which casts shadows under the eyes.
Living room
Downlights alone make a living room feel flat. Use a wider spacing, put them on a dimmer and add lamps or wall lights; living room downlights goes into the layout.
Bedroom
Keep downlights away from directly above the bed, where you’d be looking straight up at them. Place them around the edges or towards the wardrobe.
Hallway
A narrow hall or landing usually needs one row down the middle, spaced evenly enough to light the floor and stairs safely.
Fitting them
Most downlights need roughly 70 to 100 mm of space above the ceiling; low-profile models need much less. Check the depth on the spec sheet before you order, especially under a floor or a flat roof.
Under Part P of the Building Regulations in England, a new circuit, or adding to or altering a circuit within the zones around a bath or shower, is notifiable: it must be done by a registered electrician or signed off by building control. Rules differ in Wales, Scotland and Northern Ireland. Adding downlights to an existing lighting circuit elsewhere isn’t notifiable in England, but it still has to meet the wiring regulations, and new holes and cable runs are a job most people leave to an electrician.
Hand your electrician the CSV or a printout of the layout. The coordinates let them mark every position before cutting, check the grid is even, plan the cable runs and cut each hole once. Slightly irregular spacing is easy to miss on paper and obvious once the lights are on.
What I'd buy
Affiliate linksFAQs
How far apart should downlights be?
It depends on the room. On a standard 2.4 m ceiling, kitchens use 1.2 to 1.5 m and bathrooms 1 to 1.2 m, with the kitchen line about 60 cm out from the worktop wall. Living rooms and bedrooms can go wider, 1.5 to 2 m. On open walls, keep the first light about half the spacing from the wall, usually 0.6 to 0.75 m.
Do I need to know how bright each room should be?
No. The room presets set a sensible target for each room. If you want brighter or softer light, move the target slider and the tool shows the effect.
What if my room isn’t rectangular?
Split it into rectangles and work out each one separately, or enter the largest rectangle and adjust the extra section by eye. Keep the rows lined up where the two areas meet.
Does beam angle really matter?
Yes. Too narrow and you get bright pools with dark gaps between them; too wide and the light spills onto the walls and can glare. Around 50 to 60 degrees suits most rooms.
How accurate is the lux estimate?
It’s a rough guide, and a generous one. The tool divides total lumens by floor area, which gives a lumens per m² figure rather than true lux, and doesn’t allow for light lost to walls, furniture and dark surfaces, so real levels will be lower, especially in a kitchen with dark units. Use it to compare layouts, not as a measurement.
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