Recessed Lighting Calculator — How Many Can Lights Do I Need?
Enter your room size, target brightness and bulb lumens to get the number of recessed can lights, total wattage and spacing guidance. No sign-up, no data stored.
Recessed lights needed
How recessed light count is estimated
- Room area (sq ft) = length x width.
- Lumens needed = area x target foot-candles (1 fc = 1 lumen per sq ft).
- Light count = ceil(lumens needed / bulb lumens).
- Wattage = count x 9 W, a typical draw for an 800-lumen LED retrofit.
- Spacing = half the ceiling height, capped between 3 and 6 ft for comfort.
The foot-candle method is the professional shortcut: it scales linearly, so a 200-sq-ft room needs exactly double the lumens of a 100-sq-ft room at the same brightness. It ignores color and wall reflectance, which is why we recommend a dimmer rather than chasing precision.
Room size → recessed light count reference
Rough counts with 800-lumen bulbs at 30 foot-candles, 8-ft ceiling.
| Room size | Area | Lights (800 lm) | Spacing |
|---|---|---|---|
| 8x8 office | 64 sq ft | 3 | 4 ft |
| 10x10 bedroom | 100 sq ft | 4 | 4-5 ft |
| 12x12 living room | 144 sq ft | 6 | 4 ft |
| 10x14 kitchen | 140 sq ft | 6 (plus task row) | 4 ft |
| 16x20 great room | 320 sq ft | 12 | 4-5 ft |
Last updated: October 2026 · Estimates assume standard LED retrofit cans and medium-tone ceilings. Dark paint or high ceilings need 10-20% more lights.
Recessed lighting FAQ
Visually yes - a ceiling full of cans looks like an airport runway. Use the calculated count, keep rows aligned with the room, and rely on a dimmer instead of over-building. Extra lights also mean extra holes if you ever remove them.
Place task lights above the counter edge, about 12-18 in from the wall, not centered on the ceiling. The ceiling grid handles general light; the row over the counter handles prep work.
4-inch trims suit 8-ft ceilings and small rooms; 6-inch suit 9-10-ft ceilings and larger rooms. Both take the same LED retrofit. Smaller trims look cleaner in hallways and bathrooms.
Yes - use IC-rated housings wherever insulation touches the fixture, and air-tight (ICAT) housings in the ceiling below an attic to stop drafts. Non-IC housings need 3 in of clearance and are a fire risk if buried.
Match lumens, not watts. An 800-lumen LED (60W equivalent) is the standard choice; go 1,100 lumens (75-90W equivalent) for high ceilings or dark rooms, and use 650-lumen (40W) bulbs for hallways and closets.
Related calculators & guides
How Many Recessed Lights Do I Need?
The foot-candle method, spacing rules, and layout examples for every room type.
Read the guide →