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Volume of a Grecian pool

Calculate the volume of a Grecian pool (rectangle with cut corners) in gallons or litres. Free instant calculator.

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The formula

(Length × Width − 2 × Corner Cut²) × Average Depth × 7.48 = US gallons

Worked example

A Grecian pool is a rectangle with its four corners cut off at 45°. With a 30 ft × 15 ft body and 2 ft corner cuts, the area is 450 − 2 × 2² = 442 sq ft. At 5 ft average depth that's ≈ 16,530 gallons. We subtract the exact corner triangles for an accurate figure.

This calculator uses the precise cubic-foot-to-gallon value (about 7.48 US gallons per cubic foot) for your Grecian pool and lets you switch between US gallons, imperial gallons, litres, and cubic metres.

How to calculate Grecian pool volume step by step

You will need these measurements:

  1. Measure length, width, corner cut, and depth. A Grecian pool is a rectangle with the four corners cut at 45°. Measure length, width, how far each corner is cut, and the average depth.
  2. Find the area: rectangle minus the corners. Start with Length × Width, then subtract the four cut triangular corners (each corner removes ½ × cut × cut).
  3. Multiply by depth, then convert. Volume in cubic feet = surface area × depth. Multiply by 7.48 for US gallons.
Worked example

A 36 ft × 18 ft Grecian with 3 ft corner cuts, 5 ft deep: area ≈ (36 × 18) − 4 × (½ × 3 × 3) = surface area, × 5 = 3,150 cubic feet, then × 7.48 ≈ 23,564 US gallons.

Common Grecian pool sizes

Approximate capacity at 5 ft average depth, computed with this calculator. Your exact number depends on your real depth.

Pool sizeUS gallons
17 × 33 ft Grecian20,515
17 × 37 ft Grecian23,059
20 × 36 ft Grecian26,257
20 × 44 ft Grecian32,241

Grecian vs Roman: how the corners differ

A Grecian pool is a rectangle with all four corners cut off at 45 degrees, giving an eight-sided outline. The key extra measurement is the corner cut — how far in each corner is chamfered. The area is the full rectangle minus the four triangular corners, each of which removes ½ × cut × cut. Don't confuse a Grecian with a Roman pool: a Roman has rounded semicircular ends, while a Grecian has straight diagonal cuts. Measure length and width across the full rectangle as if the corners weren't cut, then measure the cut depth on one corner (they're usually symmetric). As with other in-ground shapes, average the shallow and deep depths.

Questions

Common answered

A Grecian pool is a rectangle with all four corners cut off at a 45-degree angle, producing an octagonal outline. It's calculated as the rectangle area minus the four cut corners.
Measure how far the chamfer comes in along one edge of a corner. The corners are usually symmetric, so one measurement applies to all four. Each cut removes a small triangle of area.
A Grecian has straight 45-degree cut corners; a Roman has rounded semicircular ends. They use different area formulas, so pick the calculator that matches your pool.
A 20 ft × 40 ft Grecian with about 3 ft corner cuts holds roughly 29,000 gallons at 5 ft average depth — a little less than a plain rectangle of the same size because of the cut corners.
Modestly. Each corner removes a small triangle, so a Grecian holds slightly less than the equivalent rectangle. The deeper the cut, the larger the difference.