Pool Square Footage Calculator
Measure your pool’s length and width (or diameter) and average depth, and this pool square footage calculator returns the surface area in square feet and the water volume in gallons — the two numbers behind chemical dosing, covers, and heating.
Use average depth (shallow + deep, divided by 2) for sloped pools.
Estimates only — not financial advice. This calculator gives approximate figures for planning. It is not financial, tax, or legal advice; check with a qualified professional before making decisions.
How the pool square footage calculator works
Surface area depends on the shape: a rectangle is length × width, an oval is length × width × 0.8 (an ellipse trims about a fifth off the enclosing rectangle), and a circle is π times the radius squared. That area times the average depth gives cubic feet; one cubic foot of water is 7.48 gallons.
For pools that slope from a shallow end to a deep end, average the two depths — for example 3 ft and 8 ft averages to 5.5 ft. That single number is close enough for chemical and heating estimates.
surface sq ft = shape area · gallons = sq ft × avg depth × 7.48
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Pool square footage calculator FAQ
How do I measure pool surface area?
For a rectangle, measure length × width in feet. For an oval, measure the longest length and widest width and multiply by 0.8. For a circle, measure the diameter and use π × (diameter/2)².
How many gallons is my pool from its dimensions?
Multiply the surface square feet by the average depth in feet, then by 7.48. A 32 × 16 ft pool averaging 5 ft deep is 512 sq ft × 5 × 7.48 ≈ 19,150 gallons.
Why does pool surface area matter?
Chemical dosing, solar cover sizing, and heat loss are all driven by surface area — evaporation and chemical demand happen at the surface. Volume (gallons) drives pump and filter sizing.
What is the area of an oval pool?
Length × width × 0.8. The 0.8 factor accounts for the curved ends: a 30 × 15 ft oval is 30 × 15 × 0.8 = 360 sq ft, not the 450 sq ft of the enclosing rectangle.
Which depth do I use for volume?
Average depth: (shallow end + deep end) ÷ 2. A pool sloping from 3 ft to 8 ft averages 5.5 ft. Flat-bottom pools just use the single depth.