Lighting · can light layout
Recessed light spacing calculator.
Enter the room and ceiling height. The calculator spaces recessed lights no farther apart than half the ceiling height, sets the first row a chosen distance from each wall, and gives the grid, the actual spacing and the position of each row. Feet or metres. Runs in your browser; nothing is sent or stored.
Room and ceiling
Light layout
Worked example
A 14 x 12 ft room (168 x 144 in), an 8 ft (96 in) ceiling and the first light 24 in (2 ft) from each wall. Maximum spacing = 96 / 2 = 48 in (4 ft). Usable length = 168 - 2 x 24 = 120 in, so ceil(120 / 48) = 3 gaps and 4 lights, 40 in apart. Usable width = 144 - 48 = 96 in, so ceil(96 / 48) = 2 gaps and 3 lights, 48 in apart. Total = 4 x 3 = 12 lights.
Method
Plain arithmetic. Maximum spacing = ceiling height / 2. The first row sits the wall distance you choose from each wall. Along each direction, the number of gaps = ceil(usable distance / maximum spacing), the lights = gaps + 1, and the actual spacing = usable distance / gaps, so the lights are evenly spaced and never farther apart than the maximum. Total = lights along the length x lights along the width.
Rules of thumb. Hunker (quoting Capitol Lighting), PacLights and 1000Bulbs all give ceiling height divided by two. Hunker says to keep lights within 1.5 to 3 ft of walls and PacLights says 2 to 3 ft; Hunker also mentions spacing lights twice the wall distance apart. Montreal Lighting calls the half-ceiling-height rule a starting point and says that where a spec sheet lists a spacing criterion (spacing = SC x mounting height, which accounts for beam spread and lumen performance) that is the more precise method. Use the lumens needed per room tool to check brightness. This is a layout aid, not an electrical design.
Rule of thumb, not a standard. These are design rules of thumb from published decorating guides, not building codes or standards. Treat the result as a starting point and tape it out in the room before you buy or drill. Results are shown in both imperial and metric. Conversions use 1 in = 2.54 cm and 1 ft = 0.3048 m.
Sources, each opened 2026-10-08:
- What Is The Minimum Distance Apart For Recessed Lights? (Hunker): ceiling height / 2, lights within 1.5-3 ft of walls, spacing = twice the wall distance.
- How to Plan Your Recessed Lighting Layout (PacLights): ceiling height / 2 and 2-3 ft from walls.
- Recessed Specs for Success (1000Bulbs Blog): divide ceiling height by two for the distance between fixtures.
- Recessed Lighting Spacing: Formulas and Room Examples (Montreal Lighting & Hardware): mentions the manufacturer spacing criterion: spacing = SC x mounting height.
- NIST Guide to the SI, Appendix B.8: Factors for Units Listed Alphabetically (NIST): lists 1 inch = 2.54 cm, 1 foot = 0.3048 m and 1 footcandle = 10.76391 lux.
Frequently asked questions
How far apart should recessed lights be?
Hunker, PacLights and 1000Bulbs all give a rule of dividing the ceiling height by two, so 4 ft apart under an 8 ft ceiling and 5 ft under a 10 ft ceiling. The calculator treats that as the maximum spacing.
How far should recessed lights be from the wall?
Hunker says within 1.5 to 3 ft of the walls to avoid shadows, and PacLights says 2 to 3 ft. The wall distance field is editable and defaults to 2 ft.
How many recessed lights do I need?
The calculator counts lights along each direction as ceil(usable distance / maximum spacing) + 1 and multiplies them. It is a layout count, so check the total lumens with the lumens per room calculator and the fixture lumen output.
Does beam angle change the spacing?
Yes, it can. Montreal Lighting says the spacing criterion on a fixture spec sheet (spacing = SC x mounting height) accounts for beam spread and lumen performance, and is more precise than the half-ceiling-height rule when your fixture lists one.
Is this an electrical plan?
No. It places lights on a grid. Insulation clearance, wiring, dimmers and circuit loads must meet local electrical rules, and a licensed electrician should do the work.