Above-ground pool gallons calculator
Enter the pool size, the wall height and how far below the top you fill it. The gallons are worked from the real water depth — the reason gallon charts from different brands never quite agree.
Enter your measurements
- Gallons if filled to the top of the wall
- 14,664 gal
- Water depth
- 46 in
- Water surface
- 452 sq ft
- Water in each inch of level
- 282 gal
3.1416 × (24 ft ÷ 2)² = 452 sq ft
Water depth: 52 in wall − 6 in = 46 in
452.4 sq ft × 3.833 ft × 7.48 = 12,972 gal
Quick answers for common sizes
| Example | Answer |
|---|---|
| How many gallons in a 24 ft round pool | 12,972 gal |
| How many gallons in an 18x48 pool | 6,662 gal |
| How many gallons in a 15x48 pool | 4,627 gal |
| How many gallons in a 12x30 pool | 1,904 gal |
| How many gallons in a 21 ft round pool | 9,932 gal |
| How many gallons in a 27 ft round pool | 16,418 gal |
| How many gallons in a 15x30 oval pool | 11,519 gal |
| How many gallons in an 18x33 oval pool | 15,039 gal |
Gallons at the size above, by wall height (same gap below the top)
| Wall | Gallons at your water level | Water depth |
|---|---|---|
| 30 in | 6,768 gal | 24 in |
| 42 in | 10,152 gal | 36 in |
| 48 in | 11,844 gal | 42 in |
| 52 in | 12,972 gal | 46 in |
| 54 in | 13,536 gal | 48 in |
Above-ground pools are sold by diameter (or width × length) and wall height — “24 × 52” is a 24 ft round pool with 52 in walls. But nobody fills to the top of the wall. The water usually sits around the middle of the skimmer opening, a few inches lower, and that gap is why one chart says a 24 × 52 holds about 13,000 gallons and another says 14,000.
How the calculation works
round: 3.1416 × (diameter ÷ 2)² × water depth × 7.48 oval (straight sides, round ends): [3.1416 × (width ÷ 2)² + (length − width) × width] × water depth × 7.48 rectangle: length × width × water depth × 7.48 water depth = wall height − gap below the top
Everything is in feet, and 7.48 is the number of US gallons in a cubic foot. In metric, m² × m × 1,000 gives litres.
Why manufacturer gallon charts disagree
- Water depth vs wall height. A chart that multiplies by the full 52 in overstates what you’ll put in by about 10%. Intex, for example, lists its 16 ft × 48 in frame pool at “5,061 gallons (90%)” — filled to 90% of the wall.
- Nominal size. A 24 ft pool may measure a little under 24 ft inside the wall. Intex lists 12,481 gallons for its 24 ft × 52 in pool, which works out to roughly 44 in of water in a true 24 ft circle.
- Oval formula. Above-ground ovals have straight sides; charts that treat them as ellipses come out 10–15% low.
- Rounding. Some charts round to the nearest thousand gallons. For chemical doses, that is close enough.
Gallons for common above-ground pool sizes
| Pool | 48 in wall (42 in water) | 52 in wall (46 in water) | 54 in wall (48 in water) |
|---|---|---|---|
| 12 ft round | 2,961 | 3,243 | 3,384 |
| 15 ft round | 4,627 | 5,067 | 5,288 |
| 18 ft round | 6,662 | 7,297 | 7,614 |
| 21 ft round | 9,068 | 9,932 | 10,364 |
| 24 ft round | 11,844 | 12,972 | 13,536 |
| 27 ft round | 14,991 | 16,418 | 17,132 |
| 30 ft round | 18,507 | 20,269 | 21,151 |
| 12 × 24 ft oval | 6,731 | 7,372 | 7,693 |
| 15 × 30 ft oval | 10,518 | 11,519 | 12,020 |
| 16 × 32 ft oval | 11,967 | 13,106 | 13,676 |
| 18 × 33 ft oval | 13,732 | 15,039 | 15,693 |
The most-searched sizes each have a worked page: how many gallons in a 24 ft round pool, how many gallons in an 18x48 pool, how many gallons in a 15x48 pool, how many gallons in a 12x30 pool, how many gallons in a 21 ft round pool, how many gallons in a 27 ft round pool, how many gallons in a 15x30 oval pool and how many gallons in an 18x33 oval pool. The full chart, including more sizes, is the above-ground pool size chart.
What the number is for
Chemical labels give doses per 10,000 gallons, so a pool that holds 13,000 gallons needs 1.3 times the label amount. The same figure sizes the pump (see what size pump for a 24 ft above-ground pool), the salt for a salt system, and the fill time. If you top up often, the gallons-per-inch figure tells you what each inch of evaporation costs.
What you’ll need
- Hose water flow meterBudget price
Screws onto the hose and counts gallons, so you know exactly how much went in — and your real fill rate.
See options on Amazon (opens in a new tab) - Pool test stripsBudget price
Quick daily checks. Fine for spotting a trend; use a drop kit when you’re about to add a big dose or shock.
See options on Amazon (opens in a new tab) - Solar cover (bubble cover)Mid-range price
The cheapest heating upgrade there is: cuts evaporation and holds heat in overnight. Buy the size up and trim it.
See options on Amazon (opens in a new tab)
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 do I calculate the gallons in a round above-ground pool?
Multiply 3.1416 × radius² (in feet) × water depth (in feet) × 7.48. For a 24 ft pool filled to 46 in: 3.1416 × 12² × 3.83 × 7.48 ≈ 12,972 gallons.
Should I use the wall height or the water depth?
The water depth. Most above-ground pools are filled to the middle of the skimmer, several inches below the top of the wall, so the wall height overstates the volume by 10% or so.
How many gallons are in an above-ground pool on average?
It varies hugely with size: a 12 ft × 30 in frame pool holds under 2,000 gallons, an 18 × 48 about 6,700, a 24 × 52 about 13,000 and a 33 ft round over 24,000. Use the calculator with your pool’s size.
How many litres is a 24 ft above-ground pool?
About 49,000 litres with a 52 in wall filled to 46 in. Switch the calculator to metric for any size.
Related guides
Sources
- NIST Handbook 44, Appendix C — General tables of units of measurement (opens in a new tab) — 1 US gallon = 231 cubic inches (7.48052 gallons per cubic foot).
- Intex — Ultra XTR Frame 24 ft × 52 in pool (product page) (opens in a new tab) — Lists a water capacity of 12,481 gallons for a 24 ft × 52 in pool; the fill depth is not stated.
- Intex — Ultra XTR Frame 18 ft × 52 in pool (product page) (opens in a new tab) — Lists 6,981 gallons.
- Intex — Ultra XTR Frame 16 ft × 48 in pool (product page) (opens in a new tab) — Lists “5,061 gallons (90%)” — capacity at 90% of the wall height.