Downlight calculator
How many downlights a room needs for even general light, and where they go. Enter the room's size; the answer updates as you type.
5 downlights.
- Floor area
- 12.0 m²
- Light level
- 150 lux
- Light needed
- 2,571 lm
- Grid
- 3 × 2
- Apart
- 1.3 × 1.5 m
The even grid holds 6: fit them all, or leave out one or two where a pendant or cove light already lights the room.
How it works it out
Each kind of room wants a level of light, in lux: living or dining 150, bedroom 100, kitchen 200, bathroom 150, study 200. These are for general light across the whole room; a desk, a reading chair or a kitchen counter wants a lamp or task light on top.
The floor area times that level is the light the room needs. Not all of a downlight’s light reaches the room, so it is divided by 0.7, a typical share for a small room with pale walls and ceiling; dark finishes need more. Divided by one downlight’s lumens and rounded up, that is the number of downlights, then spaced evenly, with more along the room’s length and the outer ones half a spacing from the walls.
See them switched on
Numbers say how much light; a picture says whether you like it. In Setout place downlights, cove lights, pendants, wall uplights and lamps in your plan, then turn on Lights on in 3D to see the room at night, lit by the fittings you chose.
Questions
How many downlights do I need for a living room?
A 7.5 × 3.6 m living and dining area, typical of a 4-room HDB flat, takes about 10 downlights of 600 lumens for even general light at 150 lux. Brighter fittings mean fewer of them.
How many downlights for a 4-room HDB flat?
About 19 for the bedrooms and the living and dining area at typical sizes, with 600-lumen downlights. Kitchens and bathrooms are on top: a few more each.
How far apart should downlights be?
Evenly, with the ones nearest a wall about half the spacing from it, so the edges of the room are as bright as the middle. In a small room with a 2.6 m ceiling, 1.2 to 1.8 m apart is usual.
What wattage of downlight should I buy?
Go by lumens, not watts: lumens are the light, watts the power it uses. An LED downlight of 9 to 12 watts gives roughly 600 to 1,000 lumens; check the box and enter its lumens above.