Circle Calculator · Practical guide
How Many Square Feet in a 20 Foot Circle?
The exact area of a 20-foot circle, plus what it means for materials and coverage.
At a glance
The Short Answer
A circle with a 20-foot diameter covers 314.16 square feet — π times the 10-foot radius squared (π × 100 = 314.1593).
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The Math
Area of a circle: A = πr². With a 20-foot diameter, the radius is 10 feet, so A = π × 10² = 100π ≈ 314.16 ft². If 20 feet is the radius instead, the circle is 40 feet across and the area jumps to π × 400 ≈ 1,256.64 ft² — area grows with the square of the radius, so doubling the radius quadruples the area.
20-Foot Circle at a Glance
| Property | 20-ft Diameter | 20-ft Radius |
|---|---|---|
| Radius | 10 ft | 20 ft |
| Diameter | 20 ft | 40 ft |
| Circumference | 62.8319 ft | 125.6637 ft |
| Area | 314.1593 ft² | 1,256.6371 ft² |
Putting the Number to Work
For a round patio, pool cover, or garden bed 20 feet across, 314 square feet is your coverage figure. Ordering pavers or concrete? Most suppliers suggest adding 5–10% for cuts and waste, which means planning for roughly 330 to 346 ft² of material. For edging, the circumference tells you the border length: about 62.8 feet. Enter 20 in the calculator above under Diameter mode to verify every figure.
Frequently Asked Questions
How many square feet is a 20 foot diameter circle?
314.16 square feet, from π × 10².
What if 20 feet is the radius, not the diameter?
The circle is then 40 feet across and covers about 1,256.64 square feet — four times the 20-foot-diameter area.
How much edging do I need for a 20 foot circle?
The circumference is π × 20 ≈ 62.83 feet, so plan on about 63 linear feet of edging material.
How do I convert the area to square yards?
Divide square feet by 9. A 20-foot-diameter circle covers 314.16 ÷ 9 ≈ 34.9 square yards.