How many recessed lights do I need? Calculate can lights, spacing, wattage, and costs by room type and ceiling height. Get the perfect lighting layout for any room.
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Last updated March 2026 by our expert review team
| Room Type | Lumens/sq ft | 12x12 Room |
|---|---|---|
| Living Room | 20 | 2,880 lumens |
| Kitchen | 40 | 5,760 lumens |
| Bedroom | 15 | 2,160 lumens |
| Bathroom | 40 | 5,760 lumens |
| Home Office | 30 | 4,320 lumens |
| Hallway | 10 | 1,440 lumens |
Based on IES (Illuminating Engineering Society) recommended foot-candle levels for residential spaces.
Ehsan Ghazanfari
Licensed Structural Engineer
FISE-certified structural engineer with 11+ years designing bridges, retaining walls, and foundations. MSc from Aalto University.
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Certified Cost & Estimating Professional
AACE-certified estimator working with 20+ insulation companies including the two largest franchises in America.
See full profileUpdated March 2026
How we verify our calculatorsStandard spacing: ceiling height / 2. In a room with 8-foot ceilings, space lights every 4 feet for even coverage.
Place the first light at half the spacing distance from each wall. This prevents dark corners.
LED bulbs save 75% on energy vs. incandescent and last 25,000 hours (about 8 years at 8 hrs/day). Always choose LED for new installs.
Planning the wiring? Use our conduit fill calculator to size the conduit for your lighting circuit.
Use IC-rated fixtures if insulation will touch the housing. Non-IC fixtures near insulation are a fire hazard.
Kitchens and bathrooms need 40 lumens/sq ft (double the living room). Add under-cabinet lights in kitchens for task lighting.
Enter your room dimensions and ceiling height. Select the room type, fixture size, and bulb type.
The calculator finds total lumens needed based on room type, then divides by bulb output. It also checks spacing rules (ceiling height / 2) and uses whichever number is higher.
Get the number of lights, layout grid, spacing, wattage, annual energy cost, and total material cost.
Spacing Formula
Spacing = Ceiling Height / 2
Wall Offset = Spacing / 2
Lights per Row = ceil((Length - 2 x Wall Offset) / Spacing) + 1
How many recessed lights for a 12x12 room?
6 to 9 lights depending on room type. A living room needs 6 (at 20 lumens/sq ft), a kitchen needs 9 (at 40 lumens/sq ft).
How far apart should recessed lights be?
Divide ceiling height by 2. For 8-foot ceilings, space lights 4 feet apart. For 10-foot ceilings, 5 feet apart.
What size recessed light should I use?
6-inch for general room lighting. 4-inch for accent or task lighting. 5-inch as a middle ground. 6-inch is the most common for residential.
LED vs halogen recessed lights?
LED uses 75% less energy, lasts 7x longer, and runs cooler. LED costs more upfront ($8 vs $4) but saves $30 to $50 per bulb over its lifetime.
How much does it cost to install recessed lighting?
$150 to $300 per light for new construction with wiring. $75 to $150 for remodel/retrofit into existing ceilings. DIY fixtures cost $20 to $45 each.
Do recessed lights need to be on the same circuit?
Yes, typically. A 15-amp circuit handles up to 12 LED recessed lights. A 20-amp circuit handles up to 16.
Can I install recessed lights in insulated ceilings?
Only with IC-rated (Insulation Contact) fixtures. Non-IC fixtures must have 3 inches of clearance from insulation.
How much do recessed lights cost to run?
12 LED recessed lights at 12W each cost about $50 per year running 8 hours daily at $0.12/kWh. Halogen costs about $210/year for the same setup.
A standard bedroom at 15 lumens/sq ft. Six LED can lights in a 2x3 grid provide even, comfortable illumination. Material cost: $168 to $318.
Kitchens need 40 lumens/sq ft for food prep. Twelve lights in a 3x4 grid cover the full space. Material cost: $336 to $636.
A large living room at 20 lumens/sq ft with 4.5-foot spacing from 9-foot ceilings. Material cost: $336 to $636.
Office spaces need 30 lumens/sq ft. Nine 4-inch lights give focused task lighting. Material cost: $207 to $342.
Spacing lights too far apart
Creates dark spots between fixtures. Use the ceiling height / 2 rule for even coverage across the entire room.
Not enough lumens for kitchens
20 lumens/sq ft is too dim for food prep. Kitchens and bathrooms need 40 lumens/sq ft, double the living room requirement.
Using non-IC fixtures near insulation
Non-IC rated fixtures in contact with insulation are a fire hazard. Always use IC-rated (Insulation Contact) housings in insulated ceilings.
Overloading the circuit
More than 12 LED lights on a 15-amp circuit exceeds safe capacity. Add a second circuit or upgrade to a 20-amp breaker for larger rooms.
Placing lights too close to walls
Creates harsh wall shadows and uneven lighting. Keep the first light at half the spacing distance from each wall for balanced coverage.
Important Disclaimer
These estimates are for planning purposes only. Actual costs vary by location, material availability, and project complexity. Always get at least 3 local quotes. This calculator does not replace professional advice.