Square Footage of a Circle
Calculate the area of a circle in square feet using radius or diameter. Free online circle area calculator with visual charts and instant results for construction, landscaping, and geometry.
About This Calculator
The Square Footage of a Circle Calculator helps you quickly compute the area, circumference, and diameter of any circle from its radius or diameter. Whether you're planning a circular garden, installing a round table, calculating concrete for a circular slab, or working on any geometry problem, this tool gives you instant results with visual charts.
The area of a circle is calculated using the formula A = πr², where r is the radius. The circumference (distance around the circle) is C = 2πr, and the diameter is simply d = 2r. If you have the diameter, simply divide by 2 to get the radius and apply the area formula. Enter any radius or diameter in feet to get all three measurements instantly.
Common Uses
- Construction: Calculate concrete volume for circular slabs, footings, or columns
- Landscaping: Measure circular garden beds, ponds, or patios
- Home Improvement: Estimate flooring, paving, or turf for circular areas
- Education: Verify geometry homework and understand circle properties
Frequently Asked Questions
How do you calculate square footage of a circle?
The area of a circle is calculated using the formula A = πr², where r is the radius of the circle. If you have the diameter instead, divide it by 2 to get the radius, then apply the formula.
What is the square footage of a 10 ft radius circle?
A circle with a 10 ft radius has an area of approximately 314.16 sq ft. This is calculated as π × 10² = 100π ≈ 314.16 square feet.
How many square feet is a 20 ft diameter circle?
A circle with a 20 ft diameter has a 10 ft radius. Its area is π × 10² = 314.16 sq ft. The diameter is twice the radius, so divide by 2 first.
Can I use this calculator for landscaping projects?
Yes, this calculator is ideal for landscaping, gardening, construction, and any project requiring circle area measurements in square feet.
Is this calculator free to use?
Yes, it is completely free to use with no registration or hidden charges.
Can I share my calculation results?
Yes, the URL saves your inputs so you can bookmark or share the exact calculation with others.
What is the formula for circumference of a circle?
The circumference (distance around a circle) is calculated using the formula C = 2πr, where r is the radius. If you have the diameter, you can also use C = πd.
How many square feet is a circle with a 5 ft radius?
A circle with a 5 ft radius has an area of approximately 78.54 square feet. This is calculated as π × 25 = 78.54 sq ft, or about the size of a small garden shed.