Guide
How Many Downlights Do You Need? A Room-by-Room Guide
A practical sizing guide with calculations for every room in an HDB flat or condo.
The formula
The number of downlights you need comes down to one calculation: room area in square metres, multiplied by the target lux level for that room, divided by the lumen output of each downlight. A standard 10W LED downlight produces about 800–900 lumens. Kitchens need 250–300 lux for food preparation. Living rooms need 100–150 lux for general lighting. Bedrooms need 60–100 lux. Bathrooms sit around 150–200 lux. Multiply room area by target lux to get total lumens required, then divide by lumens per fixture. Round up, then add one or two — even distribution matters more than hitting an exact number, and dimmable downlights give you the flexibility to dial back.
HDB 4-room living room (20–25 sqm)
A typical 4-room HDB living and dining area spans 20–25 square metres. At 150 lux, that's 3,000–3,750 lumens total. With 900-lumen downlights, the formula gives you 4–5 fixtures. Most electricians and lighting consultants will recommend 5–6 for this room size to ensure even coverage across both the seating area and dining zone. Position them to light the areas you actually use — over the sofa, the dining table, the TV wall — rather than in a rigid grid. A grid of equally spaced downlights looks like a commercial office.
HDB master bedroom (12–14 sqm)
The master bedroom in a 4-room or 5-room flat is typically 12–14 square metres. At 80 lux, you need about 960–1,120 lumens — just 2 downlights by the formula. In practice, 3–4 work better: two over the general area and one or two near the wardrobe. Put them on a dimmer. Bedrooms should be the dimmest room at night, and a few extra downlights on a dimmer give you more control than two fixtures running at full brightness.
Condo living room (25–30 sqm)
Condo living rooms are typically 25–30 square metres with ceilings at 2.8m or higher. At 150 lux, that's 3,750–4,500 lumens — about 5–6 downlights. The higher ceiling means light travels further before reaching the floor, so consider 12W fixtures (1,000–1,200 lumens each) instead of standard 10W. If the space is open-plan with a connected dining area, treat each zone separately and allow 2–3 additional points over the dining table.
Kitchen (8–10 sqm)
Kitchens need more light than most people expect. At 300 lux, an 8–10 square metre kitchen requires 2,400–3,000 lumens — 3–4 downlights. Place them over the sink and primary prep areas, not centred in the room. If you have under-cabinet LED strips handling the countertop, fewer ceiling downlights will do for general illumination. Without strips, make sure at least one downlight sits directly above the main work surface.
Bathroom (4–5 sqm)
At 200 lux, a 4–5 square metre bathroom needs 800–1,000 lumens. One or two downlights is sufficient. Place at least one directly above or in front of the vanity mirror — good grooming light matters more than even ceiling coverage. If you're using a backlit mirror, a single ceiling downlight in the centre handles the rest. Any fixture near the shower must be IP65 rated.
3-room and 5-room HDB adjustments
For a 3-room flat, the living room is roughly 18–20 square metres — scale down to 4–5 downlights. Bedrooms are tighter at 9–10 square metres, so 2–3 fixtures cover the space. For a 5-room flat, the living and dining area stretches to 28–37 square metres, which calls for 6–8 downlights. Common bedrooms in any flat type (9–10 sqm) need just 2–3 downlights.
Downlight spacing
The general rule: space downlights at half the ceiling height apart. For a standard HDB ceiling of 2.6m, that's about 1.2–1.3 metres between fixtures. Place the first row about 600mm from the wall to prevent dark edges. Don't obsess over perfect symmetry — prioritise placing lights over functional zones like seating areas, work surfaces, and pathways. Uneven spacing that lights the right spots beats a perfect grid that leaves your sofa in shadow.
Common mistakes
Installing too many downlights because more feels safer. Eight fixtures in a 12 sqm bedroom is overkill — you'll never run them at full brightness, and the ceiling ends up cluttered with cutouts. Choosing narrow beam angles (15–24 degrees) for general lighting. These are accent lights for artwork or shelves, not room illumination. Use 60-degree beam angles for general coverage. Forgetting that downlights aren't the only light source. Cove lighting, table lamps, and LED strips all contribute. Factor in these layers before adding more ceiling points. And skipping dimmers. Dimmable fixtures cost almost the same and give you far more control.
Recessed or surface-mounted — does it change the count?
No. Both types produce comparable lumen output at the same wattage. A 10W recessed downlight and a 10W surface-mounted downlight deliver roughly the same light. Surface-mounted fixtures sit a few centimetres lower, marginally reducing throw distance, but the practical difference is negligible. Choose between them based on aesthetics and ceiling type, not quantity. See our recessed vs surface-mounted downlights guide for a detailed comparison.
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How many downlights for a whole 4-room HDB flat?
A rough count across the whole flat: living and dining 5–6, master bedroom 3–4, common bedroom 2–3, kitchen 3–4, bathrooms 1–2 each, corridor 2–3. Total: 17–24 downlights. This varies with your layout and whether you're supplementing with cove lighting, track lights, or other sources.
Can I use fewer downlights with higher wattage?
Yes. A 12W downlight producing 1,200 lumens covers more area than a 7W at 600 lumens. Fewer, brighter fixtures can work, but check the beam angle — a high-wattage narrow-beam downlight creates a bright spot, not even coverage. Pair higher wattage with a wide beam angle (60 degrees) if you want to reduce fixture count.
What wattage for HDB downlights?
10W is the standard for general residential use, producing 800–900 lumens per fixture. 7W works for bathrooms and small bedrooms. 12W suits larger rooms or higher ceilings. Above 12W is rarely needed in residential spaces.
Should I use the same downlights in every room?
Using the same model across the flat creates a consistent look, especially in open-plan layouts where you see multiple rooms at once. However, bathrooms need IP-rated fixtures, and bedrooms benefit from dimmable models. Match the colour temperature (3000K or 4000K) across rooms for visual coherence, even if the specific fixtures differ.
Do I need an electrician?
In Singapore, all electrical work must be done by a licensed electrician. This applies to both recessed and surface-mounted installations. Budget $50–100 per light point for installation, depending on wiring complexity. New BTO flats with surface-mounted conduits are simpler and cheaper to wire than older resale flats where concealed wiring runs through a false ceiling.