How Many Recessed Lights Do I Need Calculator
Plan on one recessed light per 25–30 square feet of living space — a 200 sq ft room needs about 7–8 lights. Enter your room below and this calculator lays out the count, grid, and spacing.
General guidance only — not professional electrical advice. This calculator helps plan light counts and layouts. Hire a licensed electrician for wiring, and follow your local electrical code.
How to lay out recessed lights
The quickest layout rule: divide the ceiling height by two to get your spacing in feet. In a room with 8-foot ceilings, space recessed lights about 4 feet apart; with 10-foot ceilings, about 5 feet apart. Keep spacing at no more than one and a half times the ceiling height so the light pools overlap instead of leaving dark bands.
Start the first light half the spacing from each wall — 2 feet off the walls for 4-foot spacing. This centers the grid and stops the beams from bunching in the corners. For a feature wall or artwork, move accent lights to 1.5–3 feet from the wall to wash it with an even glow.
SwiftTools' three modes cover the whole job: estimate the count from room size, lay out an even grid at your chosen spacing, or work backwards from a fixed number of fixtures to find the spacing and wall offset that fits.
spacing = ceiling height ÷ 2 · edge distance = spacing ÷ 2 · rows × cols = total lights
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Recessed lights calculator FAQ
Is the 25–30 sq ft rule for recessed lights accurate?
Yes — for general ambient lighting in rooms with 8–9 ft ceilings, one recessed light per 25–30 sq ft gives even, shadow-free light. A 200 sq ft living room needs about 7–8 lights. The rule breaks down in kitchens and bathrooms, where task lighting needs roughly one light per 15–20 sq ft, and in rooms with very high ceilings.
How far apart should recessed lights be?
Divide the ceiling height by two: 8-ft ceilings need lights about 4 ft apart; 10-ft ceilings need about 5 ft apart. Never space them farther than 1.5 times the ceiling height or you will get dark bands between the light pools.
How far should recessed lights be from walls?
Half the spacing — about 2 ft from the walls when lights are 4 ft apart. That centers the grid and keeps beams from bunching in the corners. For washing a feature wall or artwork, move accent lights to 1.5–3 ft from the wall for an even glow.
Should I use 4-inch or 6-inch recessed lights?
Use 4-inch cans for most rooms — they look sleeker, pair well with modern LEDs, and give tighter beam control. Choose 6-inch only for rooms over about 250 sq ft or ceilings above 10 ft, where their wider spread means you can use fewer fixtures.
Do kitchens need more recessed lights than living rooms?
Yes. Kitchens and bathrooms need task lighting, so plan one light per 15–20 sq ft, plus dedicated lights over counters and islands. Living rooms and bedrooms are fine at one per 25–30 sq ft because table and floor lamps add supplemental light.
How many lumens should each recessed light have?
About 600–1,000 lumens per fixture for living spaces, aiming for 10–20 lumens per sq ft overall. A 200 sq ft room needs roughly 2,000–4,000 total lumens, so seven to eight 800-lumen LED trims cover it comfortably.
Can recessed lights be installed in a sloped ceiling?
Yes, but use slope-rated housings (rated for slopes up to about 30°) with adjustable gimbal trims so the beam points straight down. Standard flat-ceiling cans installed on a slope throw light sideways and create glare.