How many downlights you need for any room — based on Australian lux standards, ceiling height and room type. Includes grid spacing layout.
The calculator uses a lumen-based method to determine how many downlights are needed to reach a target lux level for your room type. It then works out a grid spacing layout based on the standard rule that the first row of lights sits half the spacing distance from the wall, with lights evenly distributed across the room.
The following targets are based on Australian and New Zealand lighting standard AS/NZS 1680 and general residential best practice:
| Room type | Recommended lux | Notes |
|---|---|---|
| Kitchen (general) | 300 lux | Supplement with under-cabinet task lighting over benchtops |
| Living / dining room | 200 lux | Use dimmable fittings for flexibility |
| Bedroom | 150 lux | Bedside lamps supplement general lighting |
| Bathroom | 300 lux | Vanity mirror lighting should be additional |
| Study / home office | 400 lux | Higher requirement for sustained task work |
| Hallway / passage | 100 lux | Safety and navigation — not task lighting |
| Laundry | 250 lux | Task-oriented space, good general light needed |
Lux is a measure of light falling on a surface. One lux equals one lumen per square metre. To hit a target lux level across a room, the total lumens needed equals the target lux multiplied by the room area, divided by a utilisation factor.
The utilisation factor (0.6) accounts for light that hits walls and ceilings rather than the floor or work surface. A maintenance factor (0.8) accounts for lumen depreciation as LEDs age. These are standard residential values.
A reliable rule for even downlight spacing is:
This calculator works out the actual grid (rows × columns) that best fills your room dimensions while keeping spacing even.
The calculator gives a starting point for ambient general lighting. You may want to increase the count if the room has dark surfaces (navy walls, dark timber floors) which absorb light. You may want fewer if you plan to supplement with floor lamps, pendant lights or under-cabinet lighting.
Always confirm the final layout with your electrician before cutting holes — they'll account for ceiling joists, insulation clearance and circuit load.
As a general guide, one downlight per 1.4–1.6 m² of ceiling area gives adequate general lighting for most Australian rooms at standard 2.4–2.7 m ceiling heights. The calculator uses Australian lux standards and your ceiling height to work out the correct number and suggests a grid spacing layout.
The standard rule is to space downlights at a distance equal to their mounting height from the ceiling divided by two. For a 2.4 m ceiling, that's about 1.2 m spacing. The calculator generates a grid layout based on your room dimensions and the beam angle of the globe you select.
600–900 mm from the wall is the standard range for general lighting. Downlights placed closer than 500 mm to a wall tend to wash the wall rather than illuminate the floor — useful for accent lighting but not for general room lighting. The calculator places the first row at an appropriate distance from the wall automatically.
For general bedroom lighting, 9–12W LED downlights (equivalent to 60–75W halogen) are typically sufficient at standard 2.4 m ceiling height. Living areas and kitchens benefit from 12–15W globes for higher lux levels. Always check the lumen output rather than wattage — lumen output determines how bright the light actually is.
Yes — in any ceiling with a habitable room above (such as between floors in a multi-storey home) or adjacent to a fire-rated ceiling, fire-rated downlights are required under the NCC. In single-storey homes with a roof cavity above, non-fire-rated downlights with an appropriate insulation cover are acceptable. Check with a licensed electrician for your specific situation.