Pool Cover Sizes: Chart for Round, Oval and Rectangle Pools

Above-ground pool cover sizes

Above-ground winter covers drape over the top rail and are cinched with a steel cable and winch threaded through grommets. They are labeled by the pool size they fit, and the fabric is about 3 to 4 ft (90 to 120 cm) larger to give a skirt of 1.5 to 2 ft on every side.

Above-ground pool cover sizes, round pools
Pool	Winter cover (actual)	Metric	Solar cover
12 ft round	15-16 ft round	4.6-4.9 m	12 ft, trimmed
15 ft round	18-19 ft round	5.5-5.8 m	15 ft, trimmed
18 ft round	21-22 ft round	6.4-6.7 m	18 ft, trimmed
21 ft round	24-25 ft round	7.3-7.6 m	21 ft, trimmed
24 ft round	27-28 ft round	8.2-8.5 m	24 ft, trimmed
27 ft round	30-31 ft round	9.1-9.4 m	27 ft, trimmed
30 ft round	33-34 ft round	10.1-10.4 m	30 ft, trimmed
33 ft round	36-37 ft round	11-11.3 m	33 ft, trimmed

Oval above-ground covers follow the same rule. A cover for a 15 × 30 ft oval is roughly 19 × 34 ft (5.8 × 10.4 m). Buy the cover listed for your pool's exact nominal size rather than a round cover big enough to stretch over an oval: the extra material on the sides collects water and leaves.

Air pillows

An inflatable air pillow under the center of an above-ground winter cover keeps ice from pushing on the walls and sheds rain to the edges. A 4 × 4 ft pillow is the usual choice for small and mid-size round pools; larger pools and ovals take a 4 × 8 ft pillow, or two pillows along the length of an oval. Inflate it to about half to three-quarters full so it can flex.

In-ground pool cover sizes

In-ground winter covers lie on the deck and are held by water tubes or, in some regions, by anchored straps. They need at least 2 ft (60 cm) of overlap on every side, which means the cover must be at least 4 ft longer and 4 ft wider than the pool. Most brands build in 4 to 5 ft. A cover's label normally says which pool sizes it fits; use that, and check it against the minimum below.

Minimum winter cover size for rectangular in-ground pools
Pool	Minimum cover (pool + 4 ft)	Metric	Cover perimeter	8 ft water tubes
12 × 24 ft	16 × 28 ft	4.9 × 8.5 m	88 ft	11
14 × 28 ft	18 × 32 ft	5.5 × 9.8 m	100 ft	13
15 × 30 ft	19 × 34 ft	5.8 × 10.4 m	106 ft	14
16 × 32 ft	20 × 36 ft	6.1 × 11 m	112 ft	14
18 × 36 ft	22 × 40 ft	6.7 × 12.2 m	124 ft	16
20 × 40 ft	24 × 44 ft	7.3 × 13.4 m	136 ft	17

Pool sizes match the standard sizes in the swimming pool size guide. Tube counts are the perimeter divided by 8 and rounded up; with 10 ft tubes, use about a fifth fewer.

Oval, kidney and freeform pools

Winter covers for odd shapes are sold as rectangles. Measure the longest length and the widest width of the water, add at least 4 ft to each, and buy the next rectangle up. The overlap at the curved ends and corners is larger than 2 ft; fold it under and weight it so wind cannot get beneath the cover.

Solar cover sizes

Solar (bubble) covers float on the water to hold in heat, so they should cover the whole surface without riding up the walls. They are sold slightly oversized in standard sizes and trimmed with scissors.

Rectangular pools: buy the listed size equal to or just above your pool (16 × 32 ft for a 16 × 32 ft pool) and trim to the inside of the coping.
Round above-ground pools: buy the cover listed for your pool diameter; trim if it climbs the wall.
Freeform pools: buy a rectangle covering the longest length and widest width, lay it bubble side down, let it settle for a day, then cut along the waterline.
Reels: a solar reel tube should be at least as wide as the pool. Most adjust from about 14 to 20 ft (4.3 to 6.1 m).

Solar cover thickness
Thickness	Metric	Notes
8 mil	0.20 mm	Light, cheapest, shortest life
12 mil	0.30 mm	Most common
14 mil	0.36 mm	Heavier duty
16 mil	0.41 mm	Longest life, heaviest to reel

Safety cover sizes

Safety covers are tensioned across the pool on straps anchored into the deck, so a person or pet cannot fall in. They are made to order for each pool rather than sold in stock sizes.

Overlap: the cover usually extends about 12 to 18 in (30 to 45 cm) beyond the water edge, and anchors go into solid deck around the whole pool.
Measuring: installers use the A-B method: two fixed points on the deck, with distances from each to dozens of points around the edge, steps, rocks and raised walls. That captures the true shape of freeform pools.
Standard: covers sold as safety covers in the US should state compliance with ASTM F1346, which sets load, perimeter-gap and drainage requirements and labeling for pool, spa and hot tub covers.
Mesh vs solid: mesh drains rain through and needs no pump; solid covers block all sunlight and debris but need a pump or a drain panel.

Winter covers are not safety covers

Tube-held winter covers and solar covers will not hold a child's weight, and water collecting on top is a drowning hazard. Keep the pool fenced to the CPSC barrier guidelines while any non-safety cover is on, and pump standing water off the cover.

How to measure your pool for a cover

Round pool: measure across the water from inside wall to inside wall through the center, twice at right angles. Above-ground pools are almost always the nominal size (24 ft, 27 ft).
Rectangle or oval: measure the longest inside length and the widest inside width of the water, not the deck.
Steps and benches: note any step section that extends beyond the main rectangle and include it in the length or width.
Check the deck: confirm there is at least 2 to 3 ft (60 to 90 cm) of flat deck around in-ground pools for the cover's overlap and water tubes, and that nothing (rails, slides, a diving board base) blocks it.
Add the overlap: 4 ft to each dimension for an in-ground winter cover, 3 to 4 ft to the diameter for above-ground. Solar covers: add nothing.

Tube-held covers sit on the deck, so a deck with ledges or level changes needs extra length. The deck dimensions guide helps when planning a new deck around an above-ground pool. For the rest of the backyard, patio furniture sizes and outdoor rug sizes cover what goes on the pool deck, and the trampoline guide lists clearances if both share a yard.

Frequently asked questions

Can you use a rectangle pool cover on an oval in-ground pool?

Yes. Buy a rectangle at least 4 ft longer and 4 ft wider than the oval's longest length and widest width, so it overlaps by 2 ft at the ends and the sides. The corners hang over the deck with extra material, which you fold under and weight with water tubes.

What size cover do I need for a 24 ft round above-ground pool?

A winter cover sold for a 24 ft round pool, which measures about 28 ft across so it can drape over the wall and be tied with a cable and winch. A solar cover for the same pool is about 24 ft or slightly less, trimmed to float inside the wall.

What does pool cover round size mean?

On a cover label, the round size is the pool diameter it fits, not the size of the cover itself. A cover marked '24 ft round' fits a 24 ft pool; the fabric is several feet larger. Check whether a listing gives the pool size or the actual cover dimensions.

How many water bags do I need for a pool cover?

Divide the cover's perimeter by the tube length. A 20 × 40 ft cover has a 120 ft perimeter, so 15 tubes of 8 ft or 12 of 10 ft laid end to end. Use double-chamber tubes so one leak does not free the edge.

How thick are solar pool covers?

Solar covers are sold by thickness in mils (thousandths of an inch): usually 8, 12, 14 or 16 mil, which is 0.2, 0.3, 0.36 and 0.41 mm. Thicker covers last more seasons but are heavier to roll up.

Do hot tubs use the same covers?

No. Hot tub covers are rigid foam lids made to the shell's exact outside dimensions and corner radius, and they taper from about 4 or 5 in thick in the middle to 2 or 3 in at the edges. See the hot tub size guide for how to measure.