20x40 inground pool

20x40 inground pool: size, cost and what it looks like

A 20x40 inground pool is 800 square feet of water with 120 feet of edge, and holds about 26,900 gallons at a 4.5 foot average depth. It is 5 fence panels long, a pool for entertaining on a large lot. The pool alone runs $70,000 to $200,000 at national planning rates.

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Last updated October 10, 2026

AI concept image: a large freeform pool with rounded ends, not a rectangle, beside a stone house, with a wide shelf, wall fountains, an outdoor kitchen and loungers

AI concept image, not a photo of a built pool.

Water surface: 800 sq ft
Edge: 120 ft
Gallons at 4.5 ft: 26,900
Fence panels long: 5
The pool alone, planning: $72,000 to $200,000

A 20x40 next to its neighbours, at the same scale

The shaded outline is the 20x40. The others are the sizes either side of it, drawn from the same corner, so you can see what one step adds.

Outlines, smallest to largest: 16x32, 20x40. Every outline starts at the same corner and is drawn to scale. The ticks on the top and left edges are 8 ft fence panels.

A 20x40 is 800 square feet, more than half again the water of a 16x32

Twenty by forty is a large residential pool. At 5 fence panels long it belongs on a deep, wide yard. Against a 16x32 it adds 288 square feet of water and about 9,700 gallons.

The AI concept image above shows a large freeform pool with rounded ends, not a rectangle, on an estate lot with an outdoor kitchen behind. It is a mood, not a measured 20 by 40. At this size there is room for a wide entry shelf, a spa with a spillway and a run of wall fountains without losing swimming water, and the picture shows all three.

A 20x40 suits a big lot and a big household, and needs a bigger budget to match

A 20x40 is among the sizes vinyl liner pools are commonly sold in, according to one California pool builder's size guide, so it is a standard product and not a one-off. For a crowd, ask how many will be in the water together rather than how many could fit; the people table in the guide shows the figures side by side.

Because cost follows water area and edge, a 20x40 costs far more than a 16x32 to build and to run. More water means more chemicals, more heating and a larger cover. The planning table prices the pool line for both sizes so the gap is visible.

One pool maker suggests keeping a pool to no more than about a quarter of the yard, which puts a 20x40 on a yard of about 3,200 square feet.

A pool this size also changes how the yard is used. With 120 feet of edge there is a lot of coping, deck border and fence to plan, and the equipment that circulates 26,900 gallons is larger than the kind a small pool needs. Ask the builder who services it, how long a full turnover takes, and what the cover will look like across forty feet of water. Those answers belong in the written quote, not in a phone call.

Covers, finishes, spas and decks are what grow a 20x40 price

Finishes, covers, spas and decks are the lines that grow a large pool's price, and the table below shows the pool and each extra line at its published rate. Ask every builder to price the same lines in the same order, so two quotes for a 20x40 can be compared line by line instead of by the total. A pool this size also costs more to heat and clean each year, which the running cost section of the cost page covers.

Planning cost lines for a 20x40 inground pool at national rates
Line	Planning range
The pool800 sq ft of water at $90 to $250 a square foot (shell, excavation, plumbing, equipment, plaster).	$72,000 to $200,000
Coping120 linear ft of water edge at $6 to $55 a foot, from plain concrete to travertine.	$500 to $6,500
A 4 ft deck border all round544 sq ft at $3 to $80 a square foot installed, from pavers to composite decking.	$1,500 to $44,000
Aluminum pool fence around that deck152 linear ft at $15 to $35 a foot installed.	$2,500 to $5,500
All of the above, if your quote includes it	$75,000 to $260,000

A planning range from published sources, not a quote. National rates; a state, a lot and the build type can move them a lot more than a few percent. Totals are rounded down and up to the nearest $5,000, so they will not match the sum of the lines. We price a 4 ft deck border; the builder size guide we cite suggests at least 6 ft clear around the pool, which adds deck and fence cost. The per-foot band is quoted for a standard pool and used here for every size. Left out: permits and engineering, land clearing, landscaping, electrical beyond the pool equipment, a heater, a cover, financing and overruns. Rates from: HomeAdvisor, in-ground pool cost, Fixr, gunite and concrete pool, Pool Research, plunge pool cost, Pool Research, pool coping cost, HomeAdvisor, travertine pavers, HomeAdvisor, pool deck cost, Fixr, pool fence.

More on size: the full inground pool size chart, what size pool do I need.

A design drawn at this size: French country estate pool in Highland Park, Dallas.

Pricing the whole job? Inground pool cost, line by line covers every line a 20x40 quote should carry.

See a 20x40 in your yard with the free visualizer.

Will a 20 x 40 fit your yard?

Draw your yard and the house, drop a 20 x 40 in, and see the distance to every fence. It is drawn to scale and free.

Try a 20 x 40 in my yard

Questions people ask

How many gallons is a 20x40 pool?

About 26,900 gallons at a 4.5 foot average depth, or 23,900 to 29,900 gallons at 4 to 5 feet.

How big a yard does a 20x40 pool need?

One pool maker suggests keeping a pool to no more than about a quarter of the yard, so a 20x40 suits a yard of about 3,200 square feet, plus room for a deck and a fence. Check your town's setback rules, which differ from place to place.

How much does a 20x40 inground pool cost?

At national planning rates, the pool alone comes to $70,000 to $200,000, and the full set of lines on this page reaches $75,000 to $260,000. A pool this size costs more to run too; see the yearly running cost.

Sources and date checked

Links checked October 6, 2026. If one has moved or no longer says this, tell us (see our editorial policy) and we will fix it.

Every picture on these pages is an AI concept image, not a built pool, and its proportions are not measured. Where a size has no picture of its own we show the closest one and say so in the text. Cost ranges are planning numbers from published guides at national rates, not quotes. See how we write and check pages in our editorial policy.

This page is about inground pools. A 12x24 or a 15x30 is also a common above-ground oval, which is a different product at a different price.

Pool builder? Send a homeowner their own design as a film.

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