Calculate spacing, placement, and number of recessed lights (can lights) for any room. Covers 4", 6", and 8" trim sizes with layout grids.
Recessed lighting (also called can lights, downlights, or pot lights) is the most popular ceiling light type in modern homes. But improper spacing creates dark spots, uneven lighting, or an overly bright room. This calculator applies the professional electrician's rule — spacing = ceiling height ÷ 2 — and generates a precise grid layout for your room.
The spacing rule works because typical recessed lights have a beam spread of about 90°-120°. At a distance equal to half the ceiling height, adjacent light cones overlap enough to eliminate dark spots. The calculator also adjusts for trim size (4", 6", or 8" fixtures), beam angle (narrow spot vs. wide flood), and the critical offset from walls (typically half the fixture spacing).
Beyond basic spacing, the tool generates a visual layout grid showing exact fixture placement, calculates total wattage and estimated cost, and provides guidelines for IC-rated vs. non-IC housings based on ceiling insulation. Whether you're planning a kitchen remodel or finishing a basement, this tool gives you a professional-grade lighting plan.
It gives you a credible starting layout before you start cutting ceiling holes. That is the point where spacing mistakes become expensive, especially in finished rooms. A better first layout also reduces the chance of dark corners, glare, or uneven pools of light across the room before you commit to trim and wiring locations.
Base spacing = ceiling height ÷ 2. Wall offset = spacing ÷ 2. Columns = ceil(room length ÷ spacing). Rows = ceil(room width ÷ spacing). Total lights = columns × rows. Beam diameter at floor = 2 × ceiling height × tan(beam angle ÷ 2).
Result: 8 recessed lights in a 4×2 grid, spaced 3.5' × 4' apart
Spacing = 8÷2 = 4 feet. Room is 14ft long: 14÷4 = 3.5, round to 4 columns. 12ft wide: 12÷4 = 3, but 2 rows with 4ft spacing covers well. Wall offset 2ft. Total: 4×2 = 8 lights.
The common ceiling-height-divided-by-two rule works because neighboring light cones overlap enough to smooth out bright spots and dark gaps. It is a starting point, not a hard law, and the best spacing still depends on beam angle, fixture output, and what the room is used for.
Ambient lighting for a bedroom or living room can often use a broader, simpler grid. Kitchens, vanities, and work areas usually need tighter placement or offsets that push the light toward counters and mirrors. A layout that looks evenly centered on paper can still cast shadows in the wrong place if the furniture and cabinets are ignored.
Use the result as a layout draft, then check joists, HVAC runs, insulation, and switch locations before installation. Recessed lighting is much easier to adjust in planning than after the holes are cut, especially in finished drywall ceilings.
Spacing = ceiling height ÷ 2. For 8-foot ceilings, space lights 4 feet apart. For 9-foot: 4.5 feet. For 10-foot: 5 feet. First light should be half the spacing distance from each wall.
6" is the most common and versatile. 4" provides a cleaner, more modern look with better beam control — popular in kitchens and highlighted areas. 8" is rare and mainly for commercial spaces or very high ceilings.
IC-rated (Insulation Contact) housings can safely touch ceiling insulation. Required for insulated ceilings. Non-IC must have 3" clearance from insulation. Most new installations require IC-rated — check your local code.
Typically half of the fixture spacing — so 2 feet for 4-foot spacing. For wall-washing (highlighting art or shelves), reduce to 1.5-2 feet from the wall. Never place a recessed light more than 3 feet from a wall.
LED is the clear winner: 80% energy savings, 25,000+ hour lifespan, minimal heat (important in enclosed housings), and available in all color temperatures. LED retrofit kits fit existing housings.
Highly recommended. Dimmable recessed lights let you set mood, save energy, and extend LED lifespan. Make sure your dimmer is rated for LED — old incandescent dimmers can cause flickering with LED.