Recessed Lighting Calculator – How much light is sufficient?

How much light is sufficient? When designing and specifying lighting for any place, most designers and architects apply two core principles of lighting design: the qualitative (or aesthetic) aspect of light and the quantitative (or engineering) side of light. Calculating the entire amount of lighting necessary is quantitive.

Calculate your location’s overall light output requirements using the lumen technique, the most widely used light output calculation. You can also use this page’s recessed lighting calculator to help you with your calculations. Simply choose a layout, enter the room’s size, and press the compute button.

Calculate recessed lights & ceiling spots

LED spots are an excellent option for general illumination in various rooms. For this reason, the spotlights can be recessed into the ceiling. However, it would help if you first established where the spotlights should be because a later change would necessitate a significant effort. The following criteria are significant: the appropriate number and spacing of the spots.

Parameters for Recessed Light Calculation

Parameters for Recessed Light Calculation

#1. Beam Angle

What is the angle at which the light from the spotlight emerges? For all spots, the beam angle specifies the size of the light circle that appears beneath the spot.

#2. Brightness

To obtain the necessary illuminance in the room, the brightness of a single LED spotlight is critical. Lumens are used to measure the brightness of LED spots (lm).

#3. Illuminance

The intended brightness in the room from all available light sources is described by the illuminance (in lux). The lux value represents lumens per square meter.

#4. Room Dimensions

Of course, the room’s size has a role in recessed lighting design.

Read More: Illuminance Calculator: All-to-know about Calculating Illuminance

Recessed Lighting Calculator

Recessed Lighting Calculator

About the Calculator

Lighting design can get rather complex if you wish to include all elements, especially in larger areas. Remember that the spot calculator can only provide a preliminary estimate using a simplified model.

#1. Spot Distance

The program uses a 1.5-times-the-radius-of-the-light-circle distance between two points to compute. This ensures that the light cones have a maximum overlap of half the radius of a light circle. This assures no dark spot in the middle, even with four spots arranged in a square.

#2. Increase the Distance

In most circumstances, such a generous overlapping of the light circles is not essential in a 1-row installation, such as in a narrow hallway. The distance can be reduced to slightly under twice the light circle’s radius here.

#3. Spot Quantity

A basic mathematical model is used to calculate the spot number. Even in a square room, the outcome can show an unequal amount of light depending on specific criteria. One would frequently round up or down the number for better symmetry.

#4. Minimum Brightness

The lux specification is a minimum value in the calculation as an illuminance target value. The illuminance produced by spots with modest beam angles can be much higher. Due to the narrow light circles, no uniform illumination would be feasible otherwise.

Read More: How to Convert Lumen to Watts – Lumen Watt Conversion Calculator

How to Calculate the Best Recessed Lighting Layout

How to Calculate the Best Recessed Lighting Layout

#1. Understand Your Goal

Do you wish to draw attention to a particular work of art? Are you looking for a way to bring some warm, gentle light into your home? Do you simply require extra light in your hobby or workspace without the irritation of cluttering fixtures?

Each of these objectives necessitates its own set of spacing calculations, lighting packages, and possibly installation procedures. How you go will be determined by what you require from your lighting, so take a moment to consider your goals.

#2. Start With A Sketch

At this point, your sketch is just a rough guide to help you decide which lighting kits to utilize and what spacing formula to apply. For accuracy, use graph paper and a simple scale (e.g., four squares equals twelve inches). Take your time when sketching the size of your area and everything within it. During the planning stages, accuracy is crucial.

Make a few photocopies of the document after duplicating your living environment on a sheet of graph paper. This allows you to experiment with different lighting patterns without remeasuring your room every time you make a mistake or have a new layout concept.

#3. Avoid Creating Shadowy Corners

When planning the placement of your recessed lighting, take extra precautions to ensure that your design does not result in grey areas in your home. Poorly lighted corners might make your ceiling appear lower, reducing the openness of the space and, as a result, lowering the value of your property.

This is not the effect you want to achieve, mainly if your room is already limited. To avoid gray areas, make sure the lights are at the proper distance from the wall, which is why planning and measuring are crucial.

#4. Determine the Best Layout Per Room

Now it’s time to figure out how to effectively arrange your recessed lights. In order to get the best results from the project, you should probably follow a solid formula.

Determine the Best Layout Per Room

a. The “Spacing Formula” Explained

In other words, the space between your light fixtures should be double the distance between your first light fixture and the wall. It is a basic formula, but it is based on sound theory. To begin with, keep in mind that recessed lights have a conical form. Imagine a triangle of light streaming down from the fixture to further comprehend and envision this effect.

People frequently make the error of evenly spacing their lights from the wall and one another. This causes the triangle or cone of light to overlap, leaving space between the walls unaffected. When the lights are strategically arranged, they will adequately cover the entire space without gaps or overlap. Essentially, this spacing formula ensures that light is distributed evenly and evenly throughout the space.

Read More: Aquarium Lighting Calculator – Why Is It Important?

b. Calculating the Layout for Your Space

  • General Living Space

The basic formula will suffice if you light a vast open space or a general area. Here is how you go about it:

– Determine the room’s length and width.

– Visualize or draw the room as a grid with regular rows and columns.

– Decide on how many lights there will be in each row and column.

– To get the spacing between lights, divide the whole length of the row by the total number of lights in the row.

– To estimate the distance between the wall and the first light, divide the spacing between the lights by two.

  • Highlighting a Focal Point

You should utilize the goal-based layout calculation if you wish to fulfill a specific task, such as showcasing the room’s focal point. Unless your focal point is near a wall, it will mostly be the same as the fundamental formula.

If this is the case, you will need to make the following changes:

– Measure the distance between the focal point and the ceiling (counter, floor, center table, etc.).

– To get the distance between the first light and the wall, multiply the above distance by four.

  • Wall-Washing

Recessed lighting can also be used to wash the walls. Follow these procedures to highlight a complete wall space or a hanging piece of artwork:

Recessed lighting can highlight a hanging piece of artwork
Recessed lighting can highlight a hanging piece of artwork

– Maintain a distance of 1.5 to 3 feet between your fixtures and the wall.

– Equidistant spacing between space fixtures.

– Adjustable trim should be placed away from the wall.

– Keep the fixed trim as near to the wall as possible.

#5. Space Criterion

The space criteria, also known as the SC, S/M ratio, or S/M (space to mounting height ratio), is a statistic that indicates the maximum distance between light fixtures. Online, you may get a wide range of information and opinions about SC, from different forms of indoor lighting to outside street lighting.

While you should still follow the previously described spacing calculations, keep an eye on how your spacing compares to the space criterion. Using too many lights at once can result in undesirable shadows or poor accents. Ask a professional at your local hardware shop if you are unsure.

#6. Finishing Your Lighting Plan

It is time to edit your initial sketch now that you have completed all of your calculations. If you have taken the time to make numerous drafts of your room arrangement, this is where they will come in helpful.

Finishing Your Lighting Plan

When it comes time to install your recessed lights, having a revised plan will make things go more smoothly. You can design a more exact plan with your spacing set, which will help you choose the proper light kit for your home.

Read More: Lumen Calculator – How do calculate the lumens of LED lights?


Formula: total sq. footage x 1.5 = total wattage needed.

Total wattage divided by 60 watts (or whichever wattage you select) = total amount of recessed can lights. 

Example: 240 square foot room x 1.5 = 360 divided by 60 (the bulb wattage I’d like to use) = 6 recessed lights needed


#1. How many can lights in a 20×20 room?

You should be able to use 4-inch line voltage or low voltage cans for supplemental lighting if you have a center light fixture. For a 20-foot area, we would recommend at least eight three-inch cans.

#2. Can you have too many recessed lights?

Installing recessed lights may appear to be a panacea, but they cannot adequately wash light against walls and dark corners, which would bounce reflected light into the room. Using too many recessed lights can leave portions of your room dark and increase your electric bill.

#3. How far apart should 6-inch recessed lights be?

At least 4 feet apart and 6 inches apart.

At least 4 feet apart and 6 inches apart.

#4. What size recessed light for 8ft ceiling?

Use this general rule of thumb when spacing recessed lights: divide the height of the ceiling by two to get the distance between the lights. For example, recessed lights spaced 4-feet apart should be used in an 8-foot ceiling.

#5. Is recessed lighting outdated?

The ability to modify the finishes later is one of the reasons why recessed lighting is ageless. You have an indestructible can on your ceiling. On the other hand, the finish may become outdated over time and may be acquired in a variety of colors and styles to meet your demands. You are free to alter them as frequently as you want.

Read More: LED Power Supply Guide – How to choose the best?


You should set aside some time to plan the ceiling spots and recessed lights. Any subsequent rectification would be highly costly. You can use the spot calculator to make a preliminary estimate of the number of places required.

However, a professional lighting design must account for all elements, such as the ideal placement, the optimal distance, and the reflecting behavior of the furnishings. So, our recessed lighting calculator will help you calculate pot light spacing and layout has never been easier!

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