Here are some quick tips for calculating how many recessed lights you need:
- Determine the room dimensions and layout – Measure the length and width of the room to calculate the square footage. Consider where furniture is placed and if lights are needed in specific areas.
- Decide proper lighting levels – The recommended amount of light for a living room is 20-40 footcandles. Kitchens need 30-75 footcandles. Determine the right lighting level for each room.
- Choose recessed light output – Standard recessed lights produce 600-900 lumens. High output lights produce 1200-2000 lumens. Consider light output and room size.
- Space lights appropriately – Standard lights should be spaced 4-12 feet apart. High output lights can be spaced 6-15 feet apart. Space lights evenly for uniform light.
Step 1: Determine Room Size and Layout
The first step in calculating recessed lighting is to measure the room’s dimensions and consider the layout. Use a tape measure to determine the length and width of the room in feet. Multiply the length by the width to calculate the total square footage.
It’s also important to take note of where large furniture pieces are placed and if there are specific areas in the room that need lighting, such as an art display or reading nook. This will help you plan where to place the recessed lights. Drawing a simple layout of the room with furniture placement can be helpful.
For example, if you have a living room that is 12 x 20 feet, the total square footage would be:
12 x 20 = 240 square feet
Make a note that one wall has a sofa and TV console, while another wall has bookcases. This will tell you that focused lighting is needed in the seating area for tasks like reading, as well as over the bookcases to highlight any decorative objects.
Step 2: Determine Proper Lighting Levels
The next step is deciding on appropriate lighting levels for the room. The Illuminating Engineering Society (IES) recommends the following lighting levels:
| Room | Recommended Light Level |
| Living Room | 20-40 footcandles |
| Kitchen | 30-75 footcandles |
| Dining Room | 30-50 footcandles |
| Bathroom | 30-50 footcandles |
| Bedroom | 20-40 footcandles |
| Home Office | 30-50 footcandles |
A footcandle is a unit that measures light intensity. Most homeowners want their living spaces to fall within the recommended range. Prioritize higher light levels for kitchens, workspace areas, and bathrooms where tasks are performed. Ambient lighting can be lower in bedrooms and living rooms.
Step 3: Select Appropriate Recessed Light Output
Now it’s time to choose the right recessed lights for the space. Standard recessed lights typically produce 600-900 lumens. Higher output recessed lights can produce anywhere from 1200-2000 lumens. Here are some guidelines on light output:
– Standard 5-6 inch recessed lights – 600-900 lumens
– High output 5-6 inch recessed lights – 1200-2000 lumens
– Standard 3-4 inch recessed lights – 450-700 lumens
– High output 3-4 inch recessed lights – 750-1300 lumens
Lumens measure the total amount of light emitted from a light source. To determine the right output, consider the room size as well as the lighting level you want to achieve. Standard output lights are sufficient for smaller rooms like bathrooms and laundry rooms. High output lights work well in kitchens, living rooms, and master bedrooms that need brighter illumination.
Step 4: Space Lights Properly
Recessed lights should be spaced appropriately to create uniform light distribution in the room. Here are some general spacing guidelines:
– Standard Output Lights – Space 4-12 feet apart
– High Output Lights – Space 6-15 feet apart
As a rule of thumb, standard output lights should be placed closer together while high output lights can be placed further apart. But this also depends on the ceiling height. Rooms with taller ceilings often need lights placed closer together to reach the desired light level on the floor.
In a 12×20 living room with a standard 9 foot ceiling, you might space standard 600 lumen lights 6 feet apart. For a kitchen with a 10 foot ceiling, high output 1500 lumen lights could be spaced 10 feet apart.
Create a lighting plan that distributes recessed lighting evenly throughout the space. The lights should be arranged so that the circles of light overlap slightly, eliminating dark spots between fixtures.
Calculating Total Number of Recessed Lights
Once you have the room measurements, desired light level, output of lights selected, and spacing guidelines – you can calculate approximately how many recessed lights will be needed.
Here is an example calculation:
– Living Room Dimensions: 12 x 18 feet
– Total Square Feet: 12 x 18 = 216 square feet
– Target Light Level: 30 footcandles
– Selected Lights: Standard 600 lumen output lights
– Spacing for Standard Lights: 6 feet apart
– Room Length: 12 feet
– Light Spacing: 6 feet apart
– Number of Lights Needed Along Length: 12 feet (room length) / 6 feet (light spacing) = 2 lights
– Room Width: 18 feet
– Number of Lights Needed Along Width: 18 feet (room width) / 6 feet (light spacing) = 3 lights
– Total Lights Needed: 2 (lights along length) x 3 (lights along width) = 6 lights
So for this 216 square foot living room with a target light level of 30 footcandles, six standard 600 lumen recessed lights spaced 6 feet apart should provide sufficient lighting.
Always round up when calculating total lights – it’s better to have slightly more light than not enough. You can always use dimmers later to adjust the light level if needed. Installing a few extra lights upfront provides more flexibility.
Tips for Planning Recessed Lighting
Here are some additional tips when planning recessed lighting for your space:
- Focus light over work areas like kitchen counters and office desks by placing lights closer together in those spots.
- Use high output or LED lights in rooms with cathedral or high ceilings.
- Space lights closer together if using lower light output fixtures.
- Place lights at least 4-6 inches from walls and 24 inches from cabinets for best illumination.
- Align lights with the centers of doors or windows for symmetry.
- Purchase dimmable lights if you want to control brightness.
- Have an electrician verify your lighting plan will meet code requirements.
Conclusion
Determining recessed lighting needs takes a few simple steps – measure the room size, choose appropriate lighting levels, select the lumen output, and space lights accordingly. Create a lighting plan to distribute lights evenly throughout the room. Focus extra lights in work areas and allow for some flexibility by installing a couple extra fixtures or dimmable lights. With smart planning and placement, recessed lighting can provide beautiful and functional illumination in any interior space.
