Round Pool Square Footage Calculator
Calculate round pool surface area using diameter or radius. Common above-ground sizes are 15, 18, 21, 24, 27, and 30 ft round.
Round Pool Calculator
Standard round pool sizes
Above-ground round pools come in standard diameters: 12, 15, 18, 21, 24, 27, 30, and 33 ft. Each adds significant surface area: a 15-ft round = 177 sq ft; a 24-ft round = 452 sq ft; a 30-ft round = 707 sq ft.
For surface area: π × (diameter ÷ 2)². For a 24-ft round pool: 3.14159 × 12² = 3.14159 × 144 = 452.4 sq ft.
Liner area for round pools
Round pool liner = floor (π × radius²) + walls (π × diameter × wall height). For a 24-ft round, 4-ft wall pool: floor = 452 sq ft + walls (3.14 × 24 × 4) = 301 sq ft, total ~753 sq ft.
Replacement liners are sold by pool size (24-ft round × 52 in wall, etc.) - you don't order by square footage. But knowing the area helps for chemical dosing and water volume calculations.
Pro tips
Diameter vs. radius
The radius is HALF the diameter. A "24-ft pool" has a 12-ft radius. Don't plug the diameter into the πr² formula by mistake.
Use 3.14159 for accuracy
Using 3.14 instead of 3.14159 is fine for most purposes. The difference on a 24-ft pool is less than 1 sq ft.
Add a fence-area calc
Pool code often requires fencing within X feet of the water. Calculate the fence area as a larger circle (pool radius + setback) - pool circle.
Cover allowance
Pool covers come oversized to overhang. A 24-ft round pool typically needs a 28-ft round cover for proper overlap.