Calculate the lumens needed for a room by size and activity, or find how many bulbs or fixtures are needed for a target brightness.

Lumens Per Room Calculator

How many lumens?
How many bulbs?

Pick the room and enter its size — we’ll tell you the total lumens to light it well.

Total lumens needed
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▸ How this is calculated
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Lumens Per Room Formula

The following formula is used to calculate the total lumens needed for a room. 

TL = A * LSF

Variables:

  • TL is the total lumens needed for the room
  • A is the room area in square feet
  • LSF is the lumens per square foot, which varies based on the room type and desired brightness

To calculate the total lumens needed for a room, multiply the room area by the lumens per square foot.

What are Lumens?

Lumens measure the total amount of visible light emitted by a source. The higher the lumens, the brighter the light. When planning for lighting in a room, considering the lumens is important to ensure the space is well-lit according to its use. Different activities and room types require different levels of brightness, which is why lumens per square foot can vary.

How to Calculate Total Lumens Needed for a Room?

The following steps outline how to calculate the total lumens needed for a room.

  1. First, determine the room area (A) in square feet.
  2. Next, determine the lumens per square foot (LSF) based on the room type and desired brightness.
  3. Use the formula from above = TL = A * LSF.
  4. Finally, calculate the total lumens (TL) needed for the room.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Room area (A) = 150 square feet

Lumens per square foot (LSF) = 50 lumens per square foot