Easy Pool Calc

How many gallons in an 18×33 oval pool?

Short answer

An 18 × 33 ft oval above-ground pool with a 52 in wall, filled to 46 in, holds about 15,039 gallons.

How to work it out

  1. 3.1416 × (18 ft ÷ 2)² + (33 ft − 18 ft) × 18 ft = 524 sq ft
  2. Water depth: 52 in wall − 6 in = 46 in
  3. 524.5 sq ft × 3.833 ft × 7.48 = 15,039 gal

The 18 × 33 is the big family oval: an 18 ft wide, 15 ft long straight section with 18 ft half-circles at each end. At about 15,000 gallons it is as large as many inground pools.

Adjust for your project

ft
The short side — 15 ft on a 15 × 30 oval
ft
in
The second number in the size: 52 in on a 24 × 52 pool
in
Usually the middle of the skimmer opening — check your manual. Frame pools are often filled to about 90% of the wall.
Gallons at your water level15,039 gal56,930 L
Gallons if filled to the top of the wall
17,001 gal
Water depth
46 in
Water surface
524 sq ft
Water in each inch of level
327 gal
  • Oval above-ground pools have straight sides and semicircular ends, so they hold more than an egg-shaped ellipse of the same length and width. Some gallon charts use the ellipse formula, which reads 10–15% lower.

For this job · affiliate link
Hose water flow meterAt 15,039 gal, a meter on the fill hose confirms the real volume — and every chemical dose after that is more accurate.
View on Amazon (opens in a new tab)

18×33 oval pool by water depth (52 in wall)

18×33 oval pool by water depth (52 in wall)
Water depthGallons at your water level
42 in13,732 gal
44 in14,385 gal
46 in15,039 gal
48 in15,693 gal
52 in17,001 gal

About 15,000 gallons

The surface works out to 254 sq ft for the two round ends plus 270 sq ft for the middle — about 524 sq ft. Each inch of water is about 327 gallons; at 46 in that is about 15,000.

  • Ellipse charts show about 13,400 gallons for 18 × 33 at the same depth. The straight sides are the missing 1,700 gallons — enough to throw every chemical dose off by more than 10%.
  • Doses: the 15,000-gallon pages fit closely — how much chlorine for a 15,000 gallon pool and how much salt for a 15,000 gallon pool.
  • Pump: an 8-hour turnover needs about 31 gpm.
  • Solar cover: sold by oval size; trim to the water line. At 524 sq ft, an uncovered pool this size in hot, dry weather can lose a few hundred gallons a week to evaporation.
  • Filling it: at a typical garden-hose rate of 7–8 gallons a minute, 15,000 gallons is well over a day of running water — the fill calculator works out yours from a bucket test.

Smaller oval: how many gallons in a 15x30 oval pool. A round pool of similar volume is the 27 ft round.

Different size? Use the full Above-Ground Pool Gallons Calculator.

What you’ll need

As an Amazon Associate we earn from qualifying purchases. Links to products are affiliate links — they cost you nothing extra and help keep these calculators free.

Frequently asked questions

How many gallons in an 18×33 oval pool 48 inches deep?

About 15,693 gallons with 48 in of water.

How many gallons in an 18×33×54 oval pool?

About 15,693 gallons filled to 48 in (6 in below the top).

Other common sizes

Sources