Gallons by pool size
The quick answer for the most common pools. Inground sizes at three average depths; above-ground sizes by wall height, with the water level the capacity charts assume (3.5 ft in a 48 in wall, 4 ft in 52 in, 4.5 ft in 54 in).
| Pool | 48 in wall | 52 in wall | 54 in wall |
|---|---|---|---|
| 12 ft round | 2,970 | 3,400 | 3,820 |
| 15 ft round | 4,650 | 5,310 | 5,970 |
| 18 ft round | 6,690 | 7,650 | 8,600 |
| 21 ft round | 9,110 | 10,410 | 11,710 |
| 24 ft round | 11,890 | 13,590 | 15,290 |
| 27 ft round | 15,050 | 17,200 | 19,350 |
| 30 ft round | 18,590 | 21,240 | 23,890 |
| 33 ft round | 22,490 | 25,700 | 28,910 |
| 12 × 24 ft oval | 5,950 | 6,800 | 7,650 |
| 15 × 30 ft oval | 9,290 | 10,620 | 11,950 |
| 16 × 32 ft oval | 10,570 | 12,080 | 13,590 |
| 18 × 33 ft oval | 12,270 | 14,020 | 15,770 |
| 18 × 38 ft oval | 14,120 | 16,140 | 18,160 |
| 21 × 41 ft oval | 17,780 | 20,320 | 22,860 |
| Pool | 3.5 ft avg | 4.5 ft avg | 5.5 ft avg |
|---|---|---|---|
| 12 × 24 ft rectangle | 7,540 | 9,690 | 11,850 |
| 14 × 28 ft rectangle | 10,260 | 13,200 | 16,130 |
| 15 × 30 ft rectangle | 11,780 | 15,150 | 18,510 |
| 16 × 32 ft rectangle | 13,410 | 17,240 | 21,070 |
| 18 × 36 ft rectangle | 16,970 | 21,810 | 26,660 |
| 20 × 40 ft rectangle | 20,950 | 26,930 | 32,910 |
| 25 × 50 ft rectangle | 32,730 | 42,080 | 51,400 |
How to work out the gallons by hand
Rectangle: length × width × average depth × 7.48 = gallons
Round: diameter × diameter × average depth × 5.9 = gallons
Measure in feet at the water line. For a sloped floor, average the shallow and deep depths. A 16 × 32 ft pool from 3 to 8 ft: 32 × 16 × 5.5 × 7.48 = 21,060 gallons. A 24 ft round above-ground pool with 4 ft of water: 24 × 24 × 4 × 5.9 = 13,590 gallons. The pool volume calculator handles oval, Roman, Grecian, kidney, L-shaped and freeform pools, and converts to litres.
Frequently asked questions
How big is a pool that holds 20,000 gallons of water?
About 16 × 32 ft inground with a 3 to 8 ft slope (21,000 gallons) or 18 × 36 ft at a flat 4 ft (19,400). Above ground, a 27 ft round pool with a 54 in wall holds 19,350 gallons and a 30 ft round with a 52 in wall 21,240.
What is the best pool shape?
For swimming laps, a rectangle. For the most water per foot of wall, a round pool. For chemical dosing and heating it does not matter: every dose and every heater size comes from the gallons, and this calculator gives them for every shape.
How many liters are in a 21 foot round pool?
With a 52 in wall (4 ft of water) about 10,400 gallons, which is 39,400 litres; with a 48 in wall 9,100 gallons or 34,500 litres; with a 54 in wall 11,700 gallons or 44,300 litres.
How big is a 5,000 gallon pool?
A 15 ft round above-ground pool with a 48 in wall holds 4,650 gallons, with a 52 in wall 5,310. A 12 × 24 ft oval with a 48 in wall holds 5,950 gallons. A 10 × 20 ft rectangle at 3.5 ft holds 5,240.
How many gallons is my 15x30 pool?
As an above-ground oval with a 52 in wall, 10,620 gallons; with a 54 in wall 11,950. As an inground rectangle it depends on the depth: 11,780 gallons at 3.5 ft average, 15,150 at 4.5 ft and 18,510 at 5.5 ft.