Square Footage of a Circle Calculator

Created by Luis Fernando
Reviewed by Wojciech Sas, PhD candidate
Last updated: Mar 15, 2022

This square footage of a circle calculator helps you compute the surface area in square feet, given the radius or diameter. If you want to know how to calculate the square footage of a circle, you're in the right place.

Keep reading to learn about the importance of square footage and how to calculate the square feet of a circle using the formula and our sq ft of a circle calculator.

What is the square footage of a circle?

The square footage (also known as square feet, sq ft, or SF) of a circle is its area expressed in square feet instead of other area units.

Square footage is relevant in designing different elements encountered in daily life, such as Ferris Wheels, enormous clocks, or maintenance hole covers. The area is an essential aspect of the design, as it's related to the cost of the materials used for building something, and sometimes you need to express it in square feet.

How to calculate the square footage of a circle?

If you're interested in how to calculate the square feet of a circle, you have to follow a similar process to finding the area of a circle, but you must know the radius or diameter in feet. If that's not the case, you have to convert the diameter to that unit, considering that 1 ft = 30.48 cm. Then, input the radius in the area of a circle formula, which turns out to be our SF formula:


For example, to know how to find the square feet of a circle of 1524 cm radius, follow these steps:

  1. Convert 1524 cm to ft by dividing it by 30.48. The radius in cm would be: (1524/30.48)ft = 50 ft.
    Learn more about this in our length converter.
  2. Input the radius in the SF formula:
    SF=π(50 ft)²=7854 ft².
  3. Now you know how to figure the square footage of a circle. You can check the result in our square footage calculator** by simply switching the radius units to cm and inputting 1524. Your SF should also be 7854 ft².


How to calculate the square footage of a half-circle?

  1. Remember the square footage formula of an ordinary circle, which is SF=πr².
  2. Divide it by two, as you only want the square footage of a half-circle.
  3. The result should be SF=πr²/2. That is the square footage of a half-circle for any radius.

What is the square footage of a 16-foot circle?

201.06 ft². To find the square footage of any circle:

  1. Multiply π (pi) by the diameter square: π(16 ft)² = 804.25 ft².
  2. Divide that result by four:
    804.25 ft²/4 = 201.06 ft².
  3. That's the square footage of your circle. We use the same steps when calculating the SF of a circle formula SF=πd²/4`.
Luis Fernando
Image of a circle with radius, diameter, and square footage marked.
Radius (r)
Diameter (d)
Square footage (SF)
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