About this calculator
Number of recessed (can) lights for a room from the light level it needs, laid out on an even grid with spacing from the walls.
How it’s calculated
Lumens = target lux × area ÷ 0.7 (utilisation). Fittings = lumens ÷ lumens per fitting, arranged on a grid that follows the room’s proportions. The first light sits half a spacing from each wall.
Worked example
With these inputs:
- Room length
- 16 ft
- Room width
- 12 ft
- Ceiling height
- 8 ft
- Room
- Kitchen
- Lumens per fitting
- 650
the result is:
- Fittings
- 12 lights
- Target light level
- 28 foot-candles
- Lumens needed
- 6,689
- Spacing along length
- 4'
- Spacing across width
- 4'
Tips from the trade
- Under-cabinet and task lights are extra. Don’t count them in this figure.
- Use IC-rated, airtight cans in insulated ceilings.
Results are estimates for planning and pricing. Check quantities against your drawings, the manufacturer’s data and local building codes before ordering.