Pool Cover Size Calculator
Size a pool cover correctly — the overhang past the water on every side — for a rectangular, round or oval pool.
How it works
Rect/oval cover = (length + 2·overhang) × (width + 2·overhang) · Round cover diameter = diameter + 2·overhang
A cover has to reach past the water’s edge on every side so it can anchor to the deck or coping and shed rain and leaves outward rather than into the pool. That means adding the overhang twice to each dimension — once for each side. For round and oval pools the same overhang applies to the diameter or both axes, and the area follows the circle or ellipse formula rather than a simple rectangle.
Worked example
A rectangular 8×4 m pool with a 30 cm (0.3 m) overhang needs a cover of (8+0.6)×(4+0.6) = 8.6×4.6 m, about 39.6 m², over a 32 m² water surface.
Frequently asked questions
How much overhang should a pool cover have?
Usually 15–45 cm past the water on every side so it anchors to the deck and keeps debris out. Safety covers that bolt into the surround often need more; check the cover maker’s spec.
Do I measure the water or the pool wall?
Measure the water surface — the distance across the water at its widest — then add the overhang. Measuring to the outside of a raised wall or coping would oversize the cover.
What size cover for an irregular pool?
Take the longest length and widest width to get a bounding rectangle, add the overhang, and have the cover cut to the shape. This calculator’s rectangle result is that bounding size.
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This calculator is for educational purposes. Double-check important results before acting on them.