How to Determine Ceiling Fan Blade Sweep

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Things You'll Need

  • Measuring tape

  • Calculator

Ceiling fan blade sweep refers to the distance around the circle the blades create as they turn. Knowing this number can prevent accidents from occurring by installing a ceiling fan too close to tall appliances or shelves. Knowing the ceiling fan blade sweep will also help you to choose a new fan or replace the blades on an existing fan. A correctly sized fan will efficiently cool your space.


Step 1

Measure from the center of the fan to the tip of one of the blades. Write this number down as the radius of the blade sweep.

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Step 2

Multiply the radius by 2 to determine the diameter. For instance a radius of 10 inches x 2 = 20 inches in diameter.


Step 3

Multiply the diameter by 3.14 (pi) to determine the ceiling fan blade sweep. In the example: 20 inches x 3.14 = 62.8 inches.

Step 4

Choose a replacement fan by measuring the size of your room and matching the fan blade sweep to the area of the room.


Step 5

Measure the length and width of the room in feet, and multiply them together. For instance a 10x15-foot room would have an area of 10 feet x 15 feet = 150 square feet.

Step 6

Estimate a fan blade sweep of 42 inches for rooms up to 144 square feet; a 44-inch fan for rooms between 144 and 225 square feet; a 52-inch blade sweep for rooms up to 400 square feet. Consider installing more than one fan for larger spaces.