Recessed Lighting Calculator

Calculate the exact number of recessed lights needed for your room based on dimensions, ceiling height, and desired brightness.

Room length feet Total length of the room Please enter a positive number

Room width feet Total width of the room Please enter a positive number

Ceiling height feet Determines light spacing Please enter a valid height

Room type / Brightness Sets the target foot-candles (fc) for the space

Lumens per light lm Standard 6-inch LEDs produce ~800 lm Please enter a positive number

Calculation Results

Lights needed

— fixtures

For a balanced layout, you may round up to the nearest even number.

How to use this calculator

Enter room dimensions

Input the length, width, and ceiling height of your space in feet. Ceiling height is used to determine optimal spacing.

Select the room type

Different rooms need different levels of brightness (measured in foot-candles). Kitchens need high brightness, while bedrooms need much less.

Set your fixture lumens

Enter the lumen output of the recessed lights you intend to buy. A standard 6-inch LED light typically emits 800 to 1,000 lumens.

Get your instant layout

The tool calculates the total number of fixtures required, the total lumens needed, and the optimal distance between each light.

Recessed Light Grid Layouts (Assuming 800 Lumen Fixtures)

Room Size	Room Type / Brightness	Total Lumens Needed	Fixtures Required
100 sq ft	Living Room (20 fc)	2,000	3 Fixtures
100 sq ft	Kitchen/Task (40 fc)	4,000	5 Fixtures
100 sq ft	Retail/Office (60 fc)	6,000	8 Fixtures
100 sq ft	High Detail (80 fc)	8,000	10 Fixtures
150 sq ft	Living Room (20 fc)	3,000	4 Fixtures
150 sq ft	Kitchen/Task (40 fc)	6,000	8 Fixtures
150 sq ft	Retail/Office (60 fc)	9,000	12 Fixtures
150 sq ft	High Detail (80 fc)	12,000	15 Fixtures
200 sq ft	Living Room (20 fc)	4,000	5 Fixtures
200 sq ft	Kitchen/Task (40 fc)	8,000	10 Fixtures
200 sq ft	Retail/Office (60 fc)	12,000	15 Fixtures
200 sq ft	High Detail (80 fc)	16,000	20 Fixtures
300 sq ft	Living Room (20 fc)	6,000	8 Fixtures
300 sq ft	Kitchen/Task (40 fc)	12,000	15 Fixtures
300 sq ft	Retail/Office (60 fc)	18,000	23 Fixtures
300 sq ft	High Detail (80 fc)	24,000	30 Fixtures
400 sq ft	Living Room (20 fc)	8,000	10 Fixtures
400 sq ft	Kitchen/Task (40 fc)	16,000	20 Fixtures
400 sq ft	Retail/Office (60 fc)	24,000	30 Fixtures
400 sq ft	High Detail (80 fc)	32,000	40 Fixtures
600 sq ft	Living Room (20 fc)	12,000	15 Fixtures
600 sq ft	Kitchen/Task (40 fc)	24,000	30 Fixtures
600 sq ft	Retail/Office (60 fc)	36,000	45 Fixtures
600 sq ft	High Detail (80 fc)	48,000	60 Fixtures

Frequently asked questions

How many recessed lights do I need for my room?

The number of recessed lights depends on your room's square footage and its intended use. For example, a 150 sq ft kitchen requires significantly more lights (about 11,000 total lumens) than a 150 sq ft bedroom (about 3,000 total lumens). Using this calculator provides an exact count based on industry-standard foot-candle requirements.

How far apart should recessed lights be spaced?

A standard rule of thumb in lighting design is to divide your ceiling height by two. If you have an 8-foot ceiling, space your lights roughly 4 feet apart from each other. For a 10-foot ceiling, space them about 5 feet apart. This ensures overlapping light beams and eliminates dark shadows.

How close to the wall should recessed lights be placed?

The distance from the wall should be exactly half of the distance between the lights themselves. If your lights are spaced 4 feet apart, the perimeter lights should be placed 2 feet away from the walls. If you are specifically trying to highlight wall art (wall washing), you can move them closer (1.5 to 2 feet).

What are foot-candles (fc) in lighting design?

A foot-candle is a unit of illuminance representing one lumen of light cast over one square foot of area. While "lumens" describe how much light a bulb produces, "foot-candles" describe how bright the room actually feels. Workspaces require high foot-candles (50-75), while relaxation areas require lower foot-candles (10-20).

Should I round up if the calculator gives me an odd number of lights?

In most cases, yes. Interior designers generally prefer a symmetrical grid layout (e.g., 2x3 or 3x3), which requires specific counts of lights. If the calculator says you need 5.2 lights, it is usually best to install 6 lights on a dimmer switch, ensuring both visual symmetry and adequate brightness control.

About this calculator

This recessed lighting calculator helps electricians, contractors, and DIY remodelers plan the perfect lighting grid for any room. By adhering to standard foot-candle recommendations, the tool guarantees that a space will be adequately illuminated for its specific function without being overwhelmingly bright.

The calculation runs on the following fundamental lighting design formulas:

Total Lumens Needed = Room Area (sq ft) × Target Foot-candles
Number of Lights = Total Lumens Needed ÷ Lumens per Fixture

Light Spacing = Ceiling Height ÷ 2
Wall Distance = Light Spacing ÷ 2

Remember that this calculation assumes standard beam angles (around 90 to 110 degrees) typical of modern LED can lights and wafers. If you are using narrow spot lights, you will need more fixtures placed closer together. Always install recessed lighting on dimmer switches so you can comfortably control the final output.