- 1). Measure the length, width and height of the attic in feet.
- 2). Multiply the length times the width to find the square footage of the area. For example, if your attic is 8 feet wide and 13 feet long, the square footage is 104 square feet.
- 3). Multiply the square footage by the height to calculate the volume of your attic. In the example above, if the ceiling is 10 feet tall, multiplying 104 square feet by 10 results in 1,040 cubic feet.
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