When picking LED downlights for your living room, bedroom, kitchen, or bathroom, one of the most common questions is: “How many fixtures do I need, and what wattage should each one be?”
In this guide, we’ll walk through a practical method to calculate the ideal number and wattage of downlights based on room size (m²) → target illuminance (lux) → total lumens (lm) → per-fixture wattage and quantity. We’ll also provide ready-to-use configuration tables for different room sizes, and cover other key factors such as ceiling height, spacing, beam angle, CRI, color temperature, dimming, and waterproof rating.
💡 Tip: Brightness depends on lumens (lm), while energy consumption depends on watts (W). Because luminous efficacy (lm/W) varies across products, you should always check the lumen rating first rather than relying on wattage alone.
1. Must-Read for Homeowners: The Complete Guide to Downlight Selection & Calculation
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Decide on target illuminance (lux):
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Living rooms, bedrooms, hallways: 100–300 lx (most households prefer 150–200 lx for a cozy feel).
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Kitchens and studies: 300–500 lx.
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Bathrooms: 150–300 lx.
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Calculate total lumens:
Total lumens = room area (m²) × target lux. -
Convert to fixture quantity:
Lumens per fixture ≈ wattage (W) × luminous efficacy (lm/W).
Residential downlights are typically 80–100+ lm/W. A safe estimate is 90 lm/W. -
Plan spacing and layout:
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First row should be 0.5–0.8 m (1.5–2.5 ft) away from the wall.
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Distance between fixtures ≈ 1.0–1.5 × ceiling height.
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As a rule of thumb, use 1.0–1.2 × ceiling height if you don’t have detailed photometric data.
2. Recommended Wattage & Quantity by Room Size (2.6 m ceiling, 150 lx ambient lighting)
|
Room Size |
Target Lux |
Suggested Options (focus on fixture lumens) |
Spacing Guidelines |
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3–5 m² (small foyer/hallway) |
150 lx |
5W × 2–3 pcs or 7W × 2 pcs |
0.5–0.6 m from wall; 2.6–3.1 m spacing |
|
6–10 m² (small bedroom/study) |
150 lx |
7W × 3–4 pcs or 9W × 2–3 pcs |
Grid layout |
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11–15 m² (standard bedroom/small living room) |
150 lx |
9W × 4–5 pcs or 12W × 3–4 pcs |
0.6–0.8 m from wall |
|
16–20 m² (medium living/dining) |
150 lx |
12W × 4–6 pcs or 15W × 4–5 pcs |
Combine center + perimeter |
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21–30 m² (large/open living room) |
150 lx |
12W × 6–8 pcs or 15W × 5–7 pcs |
Even spacing to avoid dark zones |
3. Example: 12 m² Bedroom
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Target: 150 lx → 12 × 150 = 1800 lm.
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Using 7W downlights (~630 lm/ea): 3 fixtures are sufficient.
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Prefer brighter? Go with 9W × 3 fixtures (~2430 lm) or 7W × 4 fixtures (~2520 lm).
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Layout: 0.6–0.7 m from walls, arranged evenly in triangle or rectangle, avoiding shadow spots near the bed or wardrobe.
4. Core Factors That Shape Your Lighting Experience
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Color temperature (CCT): 2700–3000K for warmth; 4000K neutral; 5000–6000K bright and crisp.
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Color rendering index (CRI): CRI ≥80 for most rooms; CRI ≥90 for kitchens, closets, and areas where accurate color is important.
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Beam angle: Wide (60–90°) for general lighting; narrow for accent or spotlighting.
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Dimming: TRIAC/phase dimming creates flexible ambiance.
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Waterproof rating (IP): Bathrooms, kitchens, and wet zones should use IP65 or higher.
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Cutout & fixture height: Always check compatibility with ceiling structure.
5. Quick Pre-Purchase Checklist
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Am I targeting 150 lx (cozy) or 300 lx (bright)?
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Does the total lumen output match the room requirement?
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Is spacing (distance from walls/fixtures) correct?
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Does color temperature and CRI suit the room’s purpose?
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Did I choose IP65 for wet areas?
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Do fixture cutouts match my ceiling openings?
6. Recommended LED Downlight Models
|
Model |
Wattage / Cutout |
Key Features |
Best Use Case |
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3W / 5W / 7W / 9W, 2700K–6000K |
Affordable, TRIAC dimmable |
Living rooms, bedrooms, hallways |
|
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3W / 5W / 9W |
Adjustable beam angle |
Wall art, accent lighting |
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3W / 5W / 7W |
Swivel gimbal, directional |
Display cabinets, accent spots |
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5W (2.5" cutout) |
Anti-glare design |
Bedrooms, cozy living areas |
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5W (3" cutout) |
Slim body, small cutout |
Renovations with limited ceiling space |
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5W (3" cutout) |
Narrow beam for highlights |
Artwork, focal areas |
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5/7/9/12/15, 3"–5W" cutout |
Waterproof, dustproof |
Kitchens, bathrooms, showers |
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7W / 12W |
Compact, waterproof |
Small wet-area applications |
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4/6/8/12/24W |
RGBW color-changing |
Parties, themed décor, living rooms |
Final Thoughts
Choosing the right LED downlight comes down to three steps:
(1) Decide target lux → (2) Calculate total lumens → (3) Match fixture lumens & quantity.
Once that’s done, fine-tune with ceiling height, spacing, color temperature, CRI, dimming, and IP rating. With this method, you can confidently design reliable, comfortable lighting for any room in just a few minutes.