How to calculate areas of circles
The diameter of a circle is the length of a straight line from one side of the circle to the other that passes through the central point of the circle. The diameter is twice the length of the radius (diameter = radius × 2)
The radius of a circle is the length of a straight line from the central point of the circle to its edge. The radius is half of the diameter. (radius = diameter ÷ 2)
You can measure the diameter or radius at any point around the circle – the important thing is to measure using a straight line that passes through (diameter) or ends at (radius) the centre of the circle.
When measuring circles it’s easier to measure the diameter, then divide by 2 to find the radius.
The radius is needed to work our the area of a circle.The formula is:
circle area = πR2.
π = Pi is a constant that equals 3.142.
R = is the radius of the circle.
R2 (radius squared) means radius × radius.
Therefore a circle with a radius of 7 ft, has an area of:
3.142 × 9 × 9 = 153.958 square feet or 154 sq.ft.
A circle with a diameter of 18 ft has an area:
First we work out the radius (18ft ÷ 2 = 9 ft )
Then apply the formula:
3.142 × 9 x 9 = 254.502 square feet
The area of a circle with a diameter of 18 feet is 254.5 sq.ft.
CAUTION: Your circle square feet is not what you need to purchase artificial turf. Ask us for
help to determine your actual requirements.