Where does 7.48052 come from?

A US gallon is defined as exactly 231 cubic inches and a cubic foot is 12 × 12 × 12 = 1,728 cubic inches, so a cubic foot is 1,728 ÷ 231 = 7.480519 gallons (7.48052 rounded). The calculator uses the unrounded ratio. A US gallon is exactly 3.785411784 litres, and a cubic metre is 1,000 litres.

Is it the wall height or the water depth?

The water depth. An above-ground pool is filled a few inches below the top of the wall: this page assumes 6 in, so a 48 in wall holds 42 in of water, a 52 in wall 46 in and a 54 in wall 48 in, and the size tables use those. Your pool may be filled to a different mark, such as the middle of the skimmer opening, so measure the water depth or follow the fill line in the manual; each inch of depth in a 24 ft round pool is about 282 gallons. A 24 ft round pool with a 52 in wall holds 12,972 US gal (49,106 L).

What is the difference between an oval and an oval with rounded ends?

A true oval is an ellipse: a curve with no straight part, and its area is π × a × b (π ÷ 4 × length × width). Most above-ground "oval" pools are not that: they have two straight sides and half-circle ends, so the area is a rectangle plus a circle. For a 15 × 30 ft pool with 46 in of water that is 11,519 US gal (43,605 L) with rounded ends against 10,135 US gal (38,364 L) for an ellipse, so pick the one that matches the pool. If the ends are not half circles, treat the pool as a rectangle plus two end pieces and add the volumes.

How do I find the volume of a kidney or freeform pool?

There is no exact formula, so this is an approximation. The best input is the measured surface area; a pool designer or builder often has it. Without it, enter the average length and average width, and the calculator multiplies them as if the pool were a rectangle, which is high for a curved outline. A 30 × 20 ft freeform pool with 60 in of water comes to 22,442 US gal (84,951 L) by that method, and 17,953 US gal (67,960 L) if the measured area is 480 sq ft. No correction factor is applied, since none could be sourced. To tighten it, split the outline into rectangles and circles and add them up.

How is the average depth worked out for a pool with a deep end?

For a floor that slopes evenly from the shallow end to the deep end, the average depth is (shallow + deep) ÷ 2, so 3.5 ft to 8 ft is 5.75 ft. That is exact for a rectangle with a flat, even slope, and for any outline that is symmetric end to end. Many pools have a flat shallow section, a slope and a deeper hopper, so the average is an estimate there: measure each section and add the volumes for a better figure.

How long will it take to fill my pool?

Volume ÷ flow rate. Enter your flow rate in gal/min or L/min and the calculator divides for you: the 15 ft round pool above at 10 gal/min takes about 7 h 43 min, and at 40 L/min about 7 h 18 min. The flow rate is yours to enter because it varies with the water pressure, the hose size and length, and any splitter or pump; to measure it, time how long a bucket of known size takes to fill and divide. Filling from more than one hose adds their flows.

Can I use this to work out how much chemical to add?

No. Dosing depends on the product, its strength and its label, and this calculator does not cover it. Use the volume it gives with the directions printed on the product you are using, and if you are unsure of the dose, ask the product maker or a pool professional.

How many litres or cubic metres is that?

The result shows litres beside gallons: a US gallon is 3.785411784 L, so 1,000 gallons is 3,785 L, and a cubic metre is 1,000 L. Imperial (UK) gallons, at 4.54609 L each, are listed under the result. Switch the unit to m to enter lengths in metres and see the volume in cubic metres.

Pool Volume Calculator: How Many Gallons Does My Pool Hold?

A 15 ft round pool with 42 in of water (a 48 in wall filled 6 in below the top) holds 4,627 US gal (17,514 L). That is the surface area, π × 7.5² = 176.7 sq ft, times the depth, 3.5 ft, which is 618.5 cu ft, times 7.48052 gallons per cubic foot. Pick the shape, enter the size and the depth of the water (not the wall), and add a flow rate to see how long the pool takes to fill.

Figures based on the sources listed belowUpdated 2026-10-04How we calculate

ShapeMost above-ground "oval" pools are straight sides with half-circle ends, not a true ellipse, and the two differ by about 10%. Pick the one that matches the pool.

Diameter (in)

Inside diameter of the water surface. 15 ft is 180 in.

Water depth (shallow end if sloped) (in)

Depth of the water, not the wall. An above-ground pool is usually filled a few inches below the top of the wall (this page assumes 6 in): a 48 in wall holds about 42 in of water. For an in-ground pool, 4 ft is 48 in.

FloorA sloped floor is averaged: (shallow + deep) ÷ 2. That is exact for a floor that slopes evenly over the whole length, and an estimate if there is a flat shallow section or a deeper hopper.

Fill flow rate (optional)

For the time to fill. Hose and pump flow vary with pressure and hose size, so none is assumed: time how long a bucket of known size takes to fill, or use the pump’s rated flow.

Flow rate unit

4,627 US gal (17,514 L)

Volume: 618.5 cu ft (average depth 42 in)
Imperial gallons: 3,853 imperial gallons
Time to fill: enter a flow rate in gal/min to see this

Shopping list

Tape measure (100 ft)
Measuring wheel
Hose water flow meter
5 gallon bucket (to time your flow)
Hose splitter

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Gallons in round above-ground pools by wall height

Water stands 6 in below the top of the wall (an assumption: 42, 46 and 48 in of water for the 48, 52 and 54 in walls). US gallons, worked by this calculator and rounded to the nearest gallon. The last column is how much one inch of water adds.
Diameter	48 in wall	52 in wall	54 in wall	Per inch of depth
12 ft	2,961	3,243	3,384	71
15 ft	4,627	5,067	5,288	110
18 ft	6,662	7,297	7,614	159
21 ft	9,068	9,932	10,364	216
24 ft	11,844	12,972	13,536	282

Gallons in oval above-ground pools: rounded ends or true ellipse

52 in wall, 46 in of water (6 in below the top). "Rounded ends" is a rectangle plus two half circles, which is how most oval above-ground pools are built; the ellipse column is the same overall size as a true ellipse and is smaller. US gallons, worked by this calculator. Sellers’ charts for these sizes can be lower (one lists about 10,620 gal for 15 × 30 ft), perhaps from a different fill depth; check your pool’s data sheet.
Pool size	Oval, rounded ends	Oval, true ellipse
12 × 24 ft	7,372	6,486
15 × 30 ft	11,519	10,135
18 × 33 ft	15,039	13,378

Gallons in rectangular pools by depth

US gallons, worked by this calculator. The last column is a floor that slopes evenly from 42 in of water at the shallow end to 96 in at the deep end, which averages 69 in.
Pool size	48 in deep throughout	60 in deep throughout	42 in sloping to 96 in
12 × 24 ft	8,618	10,772	12,388
14 × 28 ft	11,729	14,662	16,861
16 × 32 ft	15,320	19,150	22,023
20 × 40 ft	23,938	29,922	34,410

Methodology & assumptions

Volume = water surface area × average water depth, then converted to gallons. The shapes: a rectangle is length × width; a round pool is π × (diameter ÷ 2)²; a true oval (an ellipse) is π × a × b, with a and b the half lengths of its two axes, which is π ÷ 4 × length × width; an oval with rounded ends, which is what most above-ground "oval" pools are, is a rectangle plus a circle: with s the shorter side (the width, which is also the diameter of the two half-circle ends) and l the overall length, the area is (l − s) × s + π × (s ÷ 2)². For a 15 × 30 ft pool that is 401.7 sq ft against 353.4 sq ft for the ellipse, so the choice matters. Freeform and kidney pools have no formula. If you have measured the surface area, enter it and it is used as is; if not, the calculator multiplies the average length by the average width, which treats the outline as a rectangle and so over-counts a curved pool. Both are approximations, and no correction factor is applied, because no source for one (such as a flat percentage for a kidney shape) could be found. For a better figure, split the outline into rectangles, circles and half circles, find each volume and add them. Depth: enter the depth of the water. For a floor that slopes uniformly from the shallow end to the deep end the average depth is (shallow + deep) ÷ 2, exact for a rectangle with a planar floor and for any outline that is symmetric end to end, but only an estimate where the floor has a flat shallow section, a slope and a deeper hopper (average each section, or split the pool by sections). Above-ground pools: the tables assume the water stands 6 in below the top of the wall, a common fill height (about the middle of the skimmer opening), so a 48 in wall holds 42 in of water. Check your pool’s fill line; every inch of depth is about 110 gallons in a 15 ft round pool. Conversions are exact definitions: a US gallon is 231 cubic inches and a cubic foot is 1,728 cubic inches, so 1 cu ft = 1,728 ÷ 231 = 7.48052 US gal; 1 US gal = 3.785411784 L; 1 m³ = 1,000 L; 1 imperial gallon = 4.54609 L (the imperial figure is shown beside the result). Time to fill = volume ÷ the flow rate you enter, in gal/min or L/min, assuming a steady flow; hose and pump flow change with pressure, hose size and length, so none is assumed, and a pool that is topped up during the fill takes longer. Metric toggle: lengths in m, depths and diameter in cm, surface area in m², volume in m³. This calculator is only about the volume of water. Chemical dosing depends on the product and its label and is not covered; follow the label directions for the product you use, with the volume above.

NIST Handbook 44, Appendix C, General Tables of Units of Measurement: the US gallon is 231 cubic inches, 3.785411784 litres
Weights and Measures Act 1985, Schedule 1 (UK), Units of measurement: the imperial gallon is 4.54609 litres
ProPools, Round Above Ground Pools by Size (retailer chart of 12 to 24 ft round pools in 48, 52 and 54 in walls with their gallons): the 52 in figures for 15 to 24 ft agree with this calculator’s 6 in fill-depth assumption to within a few gallons and the 54 in figures to within about 1%; the 12 ft figures on the chart are higher, so check your pool’s own data sheet, since sellers’ capacities differ
Galaxy Home Recreation, Above ground pool buyers guide: standard oval sizes of 12 × 24, 15 × 30 and 18 × 33 ft with a seller’s capacities for 52 in walls (about 10,620 gal for 15 × 30 ft), which are lower than this calculator’s rounded-end figure
Royal Swimming Pools knowledge base, How to add water and pool accessories on your above ground pool, and Inyo Pools, How To Assemble an Above Ground Pool, Part 6, Installing the Skimmer: the water level is set by the skimmer opening, so the fill height is an estimate (this page assumes 6 in below the top of the wall); use your pool manual’s fill line
Geometry: area of a circle (π r²), an ellipse (π a b) and a rectangle with semicircular ends (a rectangle plus a circle). The oval and freeform handling above is this site’s own description of that geometry, not a standard

How to calculate the volume of a pool

Pick the shape. Rectangle, round, oval with rounded ends (straight sides and half-circle ends), true oval (an ellipse) or freeform.
Measure the water surface. Measure the length and width of the water, or the diameter of a round pool. For a freeform pool, measure the surface area if you can, or the average length and width.
Measure the water depth. Measure the depth of the water, not the wall. For a pool with a deep end, measure both ends and the calculator averages them.
Multiply. Surface area × average depth gives cubic feet; multiply by 7.48052 for US gallons, or by 28.317 for litres.
Add your flow rate. Divide the volume by the flow rate in gallons or litres per minute for the time to fill.

Worked examples

Project	Result
15 ft round pool, 48 in wall, water 42 in deep	4,627 US gal (17,514 L), 618.5 cu ft
24 ft round pool, 52 in wall, water 46 in deep	12,972 US gal (49,106 L), 1,734.2 cu ft
16 × 32 ft rectangle sloping from 42 in to 96 in of water (average 69 in)	22,023 US gal (83,365 L), 2,944 cu ft
15 × 30 ft oval with rounded ends, 46 in of water	11,519 US gal (43,605 L), 401.7 sq ft of surface
The same 15 × 30 ft size as a true ellipse, 46 in of water	10,135 US gal (38,364 L), 353.4 sq ft of surface
Freeform pool, 30 ft average length × 20 ft average width, 60 in of water (approximation)	22,442 US gal (84,951 L), 600 sq ft of surface
The 15 ft round pool at 10 gal/min	4,627 US gal (17,514 L), fills in about 7 h 43 min at 10 gal/min

Frequently asked questions

How many gallons does my pool hold?: Multiply the water surface area by the average depth of the water, in feet, to get cubic feet, then multiply by 7.48052 gallons per cubic foot. A 15 ft round pool with 42 in of water: π × 7.5² = 176.7 sq ft × 3.5 ft = 618.5 cu ft × 7.48052 = 4,627 US gal (17,514 L). A 16 × 32 ft rectangle sloping from 42 in to 96 in of water averages 69 in: 22,023 US gal (83,365 L).
Where does 7.48052 come from?: A US gallon is defined as exactly 231 cubic inches and a cubic foot is 12 × 12 × 12 = 1,728 cubic inches, so a cubic foot is 1,728 ÷ 231 = 7.480519 gallons (7.48052 rounded). The calculator uses the unrounded ratio. A US gallon is exactly 3.785411784 litres, and a cubic metre is 1,000 litres.
Is it the wall height or the water depth?: The water depth. An above-ground pool is filled a few inches below the top of the wall: this page assumes 6 in, so a 48 in wall holds 42 in of water, a 52 in wall 46 in and a 54 in wall 48 in, and the size tables use those. Your pool may be filled to a different mark, such as the middle of the skimmer opening, so measure the water depth or follow the fill line in the manual; each inch of depth in a 24 ft round pool is about 282 gallons. A 24 ft round pool with a 52 in wall holds 12,972 US gal (49,106 L).
What is the difference between an oval and an oval with rounded ends?: A true oval is an ellipse: a curve with no straight part, and its area is π × a × b (π ÷ 4 × length × width). Most above-ground "oval" pools are not that: they have two straight sides and half-circle ends, so the area is a rectangle plus a circle. For a 15 × 30 ft pool with 46 in of water that is 11,519 US gal (43,605 L) with rounded ends against 10,135 US gal (38,364 L) for an ellipse, so pick the one that matches the pool. If the ends are not half circles, treat the pool as a rectangle plus two end pieces and add the volumes.
How do I find the volume of a kidney or freeform pool?: There is no exact formula, so this is an approximation. The best input is the measured surface area; a pool designer or builder often has it. Without it, enter the average length and average width, and the calculator multiplies them as if the pool were a rectangle, which is high for a curved outline. A 30 × 20 ft freeform pool with 60 in of water comes to 22,442 US gal (84,951 L) by that method, and 17,953 US gal (67,960 L) if the measured area is 480 sq ft. No correction factor is applied, since none could be sourced. To tighten it, split the outline into rectangles and circles and add them up.
How is the average depth worked out for a pool with a deep end?: For a floor that slopes evenly from the shallow end to the deep end, the average depth is (shallow + deep) ÷ 2, so 3.5 ft to 8 ft is 5.75 ft. That is exact for a rectangle with a flat, even slope, and for any outline that is symmetric end to end. Many pools have a flat shallow section, a slope and a deeper hopper, so the average is an estimate there: measure each section and add the volumes for a better figure.
How long will it take to fill my pool?: Volume ÷ flow rate. Enter your flow rate in gal/min or L/min and the calculator divides for you: the 15 ft round pool above at 10 gal/min takes about 7 h 43 min, and at 40 L/min about 7 h 18 min. The flow rate is yours to enter because it varies with the water pressure, the hose size and length, and any splitter or pump; to measure it, time how long a bucket of known size takes to fill and divide. Filling from more than one hose adds their flows.
Can I use this to work out how much chemical to add?: No. Dosing depends on the product, its strength and its label, and this calculator does not cover it. Use the volume it gives with the directions printed on the product you are using, and if you are unsure of the dose, ask the product maker or a pool professional.
How many litres or cubic metres is that?: The result shows litres beside gallons: a US gallon is 3.785411784 L, so 1,000 gallons is 3,785 L, and a cubic metre is 1,000 L. Imperial (UK) gallons, at 4.54609 L each, are listed under the result. Switch the unit to m to enter lengths in metres and see the volume in cubic metres.

Handy tools

Unit Converter: Convert the result to another volume unit, or a measurement from feet and inches to metres.