Plan an even grid of recessed (can or pot) lights. Enter the room size, ceiling height and light size to get the number of lights, the spacing between them, how far the first row sits from the wall, and a scaled ceiling plan with measuring marks.
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Typical LED wafer/retrofit: 600–900 lm
Enter your values to see the result.
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How to use the Recessed Lighting Layout Calculator
Choose feet or meters and enter the room length, width and ceiling height.
Pick the light size and a spacing rule. Ceiling height ÷ 2 is the common rule for even general lighting.
Optionally enter lumens per light to check the brightness you will get.
Read the number of lights, spacing and wall distance, then use the ceiling plan and layout marks to mark the ceiling.
How the layout is calculated
Recessed lights look best in a regular grid where every light is the same distance from its neighbors and the outer lights sit half that distance from the walls. The calculator uses:
Target spacing = ceiling height ÷ 2 (or about 1 ft per inch of trim at an 8 ft ceiling, or your own value)
Lights per row = round(room length ÷ target spacing), at least 1; rows = round(room width ÷ target spacing)
Actual spacing = room length ÷ lights per row; wall offset = actual spacing ÷ 2
Example: a 16 × 12 ft room with an 8 ft ceiling has a 4 ft target spacing. 16 ÷ 4 = 4 lights per row and 12 ÷ 4 = 3 rows, so you need 12 lights spaced 4 ft apart and 2 ft from each wall.
Typical spacing by ceiling height
Ceiling height
Spacing (height ÷ 2)
Distance from wall
8 ft (2.4 m)
4 ft (1.2 m)
2 ft (0.6 m)
9 ft (2.7 m)
4.5 ft (1.4 m)
2.25 ft (0.7 m)
10 ft (3.0 m)
5 ft (1.5 m)
2.5 ft (0.76 m)
12 ft (3.7 m)
6 ft (1.8 m)
3 ft (0.9 m)
Layout tips
In kitchens, center the row over the front edge of the countertop (about 12–18 in from the upper cabinets) so you don't cast a shadow while working.
Over a dining table or island, use pendants or a separate row centered on the furniture instead of the room grid.
For wall washing or art, place lights 18–36 in from the wall and closer together.
Put lights on a dimmer: a grid sized for bright tasks can be dimmed for evenings.
Frequently asked questions
How far apart should recessed lights be?
A widely used rule is to divide the ceiling height by 2: an 8 ft ceiling gets lights about 4 ft apart and a 10 ft ceiling about 5 ft apart. Another rule ties spacing to the trim size: about 4 ft for 4-inch lights and 6 ft for 6-inch lights at an 8 ft ceiling. Wider spacing saves fixtures but leaves darker spots between lights.
How far from the wall should recessed lights be?
For even general lighting place the first row at about half the spacing between lights, which is usually 2 to 3 ft from the wall. Placing lights closer than about 18 inches creates bright scallops on the wall, which is only wanted for wall washing or highlighting art.
How many recessed lights do I need for a 12×12 room?
With an 8 ft ceiling and 4 ft spacing, a 12 × 12 ft room gets a 3 × 3 grid of 9 lights. Using 6-inch lights spaced about 6 ft apart, it needs a 2 × 2 grid of 4 lights. Enter your room above to compare.
Should I use 4-inch or 6-inch recessed lights?
Six-inch lights spread light more widely and suit general lighting in living rooms and bedrooms. Four-inch (and 3-inch) lights give a cleaner look and more focused light, so they are popular in kitchens, bathrooms and hallways, but you usually need more of them.
How does the calculator pick the number of lights?
It divides each room dimension by the target spacing and rounds to the nearest whole number (at least one). It then spreads the lights evenly, so the actual spacing is the room length divided by the number of lights and the wall offset is half of that.
Do I need to worry about joists?
Yes. Joists, ducts, pipes and wiring may sit exactly where a light should go. Small shifts of a few inches are fine; keep the rows straight and the spacing as even as you can, and use IC-rated housings where insulation touches the fixture.
Is my data sent anywhere?
No. Everything is calculated in your browser.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.