How many LED lights do you need to illuminate a room?

What is the sufficient amount of lighting? How to calculate the number of LEDs in order to create a good lighting environment has always been a problem, and the calculation process may become quite complicated in some specific environments.

The following design concepts will help you determine the number of LED lights needed to create a good lighting environment, and the same set of rules apply to both commercial and residential applications.



This is a unit for measuring the amount of luminescence. Whether it is LED, fluorescent, halogen or incandescent, lumens can be used to indicate light intensity. It is also known as “brightness” or “light output”, and a standard 100-watt incandescent bulb produces about 1500 to 1700 lumens of light.



Watt is not a unit for measuring brightness. It is the amount of electricity that the bulb consumes when it reaches the marked brightness. The type of light source (LED, fluorescent, halogen or incandescent) varies from lumen to watt. In the discussion below, we will use lumens as a unit of measure to ensure adequate illumination in space.


Power equivalent / watt equivalent

Now that we have combined Watt and Lumen into a concept, the wattage of the bulb will be better discussed. For example, a 100 watt incandescent lamp lumen is the same as a 10 watt LED bulb, and the 10 watt LED bulb may be labeled “100 watts equivalent” on the label.

The figure below is a power equivalent table. Even between LED products, there are subtle differences in lumens per watt, such as linear suspension LEDs, self-adjusting embedded LEDs or linear embedded LEDs.


Efficiency refers to the number of lumens emitted by the bulb in watts. The higher the number, the higher the luminous efficiency of the bulb. For example, an illumination product labeled with an Energy Star has a high luminous efficiency, which means that the amount of electricity consumed is small compared to a similar product.


Determine the space area

Use the length of the room to multiply the width of the room to get the size of the room. For example, a room 10 feet wide and 10 feet long, then his area is 100 square feet.

Footlights indicate the brightness of a light source measured from a distance of one foot. The specific lighting needs depend on the type of room being illuminated. For example, the bathroom and kitchen require more foot candles than the living room and bedroom.

Lumens are the units that measure light intensity. In order to calculate the required lumens, the first known unit area luminous flux requirement and room area are then multiplied. For example, a 100-square-foot living room requires a luminous flux of about 10 to 20 feet per unit area, and the required lumens is 1000-2000. A 100-square-foot dinner area that requires a luminous flux of approximately 30 to 40 feet per unit area, and the required lumens is 3000-4000.

For spaces that meet an average area of ​​250 square feet, the primary source has an intensity of approximately 5,000 lumens (equivalent to 20 lumens per square foot). The light intensity required at the dinner table should be about 30 lumens per square foot (just enough to illuminate the food), assuming the table is 6 feet by 3 feet and the total lumen is 540.

However, please note that these numbers are only the reference values ​​in some specific cases. If your home’s walls or furniture are dark, or if your home is decorated with some decorations that cast shadows, you may add an additional 10 lumens per square foot of lumens. All of the above calculations assume that the ceiling is 8 feet high. Of course, your personal preferences will play a decisive role in the design. If you want the room to be a little brighter, you can increase the calculation by 10% to 20%. In fact, the best design for most spaces is to install a dimmer to reduce the level of illumination to the desired level at any time.


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