Select a pool shape, enter your dimensions, and get an instant volume in US gallons, UK gallons, liters, and cubic meters.
Pool Volume Quick Reference Chart — US Gallons by Size & Depth
All volumes in US gallons — multiply by 3.785 for litres, or use the calculator’s toggle above. Above-ground depths are water depth (wall height minus ~6 inches); in-ground depths are the average of shallow and deep ends. Stock tanks (8′–12′ round) typically hold 24″–30″ of water.
| Shape | Dimensions | 30″ | 36″ | 42″ | 48″ | 52″ |
|---|---|---|---|---|---|---|
| Above-Ground Pools — Gallons at Water Depth | ||||||
| Round | 8′ diam | 940 | 1,150 | — | — | — |
| Round | 10′ diam | 1,450 | 1,750 | 2,050 | — | — |
| Round | 12′ diam | 2,100 | 2,550 | 2,950 | 3,400 | — |
| Standard Above-Ground Pools | ||||||
| Round | 15′ diam | 3,300 | 3,950 | 4,650 | 5,300 | 5,700 |
| Round | 16′ diam | 3,750 | 4,500 | 5,300 | 6,000 | 6,500 |
| Round | 18′ diam | 4,750 | 5,700 | 6,700 | 7,600 | 8,200 |
| Round | 20′ diam | 5,900 | 7,100 | 8,200 | 9,400 | 10,200 |
| Round | 24′ diam | 8,500 | 10,200 | 11,800 | 13,500 | 14,700 |
| Rectangular | 12′ x 24′ | — | 6,500 | 7,500 | 8,600 | 9,300 |
| Rectangular | 15′ x 30′ | — | 10,100 | 11,800 | 13,500 | 14,600 |
| Oval | 12′ x 24′ | — | 5,100 | 5,900 | 6,800 | 7,300 |
| Oval | 15′ x 30′ | — | 7,900 | 9,300 | 10,600 | 11,500 |
| Shape | Dimensions | 4′ avg | 4.5′ avg | 5′ avg | 5.5′ avg | 6′ avg |
|---|---|---|---|---|---|---|
| In-Ground Pools — Gallons at Average Depth | ||||||
| Rectangular | 12′ x 24′ | 8,600 | 9,700 | 10,800 | 11,800 | 12,900 |
| Rectangular | 16′ x 32′ | 15,300 | 17,200 | 19,200 | 21,100 | 23,000 |
| Rectangular | 18′ x 36′ | 19,400 | 21,800 | 24,200 | 26,700 | 29,100 |
| Rectangular | 20′ x 40′ | 23,900 | 26,900 | 29,900 | 32,900 | 35,900 |
| Kidney | 16′ x 30′ | 9,800 | 11,000 | 12,200 | 13,400 | 14,600 |
| Oval | 18′ x 36′ | 15,200 | 17,100 | 19,000 | 20,900 | 22,800 |
Litres: multiply by 3.785. UK gallons: multiply by 0.833. Cubic meters: divide litres by 1,000.
Frequently Asked Questions About Pool Volume
Multiply your pool’s surface area by its average water depth, then convert cubic feet to gallons by multiplying by 7.48. The area formula depends on the shape — length × width for rectangles, π × radius² for circles, and different combinations for oval, kidney, L-shaped, and oblong pools. Average depth is the shallow end depth plus the deep end depth, divided by two. Select your shape in the calculator above to apply the correct formula automatically without doing the math by hand.
If your pool has a sloped bottom, measure both the shallow end depth and the deep end depth and enter both — the calculator averages them for you. If your pool has a flat, uniform floor (most above-ground pools and some spas), enter the same value in both fields. Using only the shallow-end number on a sloped pool will noticeably understate your true volume, since the deep end typically holds a large share of the total water.
For irregular pools without a standard geometric shape, use these practical methods: 1) Approximate with the closest shape — most freeform pools can be estimated as a kidney or oval, which our calculator supports. 2) Break into sections — mentally divide the pool into rectangles, circles, and triangles, calculate each separately, then add them. 3) The water meter method — for an exact measurement (especially useful during an initial fill), record your water meter reading before and after filling. Subtract normal household usage for the period. Each cubic foot of water is 7.48 gallons.
Yes — nearly every pool chemical is dosed per gallon or per 10,000 gallons, so your calculated volume is the starting point for chlorine, shock, pH, and stabilizer dosing. Once you know your gallons from the calculator above, use that number with your chemical product’s per-gallon or per-10,000-gallon dosing instructions to get the right amount.
The cost depends on your pool size, local water rates, and whether you use a garden hose or a water delivery service. In the US, municipal water typically costs $0.003–$0.015 per gallon, so filling a 20,000-gallon pool runs about $60–$300. Truck delivery (bulk water) costs $0.03–$0.10 per gallon — $600–$2,000 for the same pool, but fills much faster. In Europe, water rates are higher: Germany averages €5–€10 per cubic meter (1,000 litres), and France €4–€5 per m³. Once you know your exact volume from the calculator above, multiply it by your local rate per gallon to estimate your fill cost.
A US gallon equals 3.785 litres (128 fluid ounces), while a UK (imperial) gallon equals 4.546 litres (160 fluid ounces). To convert: multiply US gallons by 0.833 to get UK gallons, or multiply UK gallons by 1.201 to get US gallons. Our calculator displays both side by side so you do not need to do the math manually. Always check which gallon your chemical product uses — US brands use US gallons, while UK, Canadian, and Australian products often reference imperial gallons or litres.
Multiply US gallons by 3.785 to get litres. For example: 10,000 US gallons x 3.785 = 37,850 litres. To go the other way, divide litres by 3.785. Our calculator has a built-in toggle — switch between US/UK gallons and litres/cubic meters with one click after calculating. If you are entering dimensions in meters rather than feet, use the Feet / Meters toggle in Step 2 before typing your measurements.
Manufacturer spec sheets often list the pool’s nominal outer-wall size, not its actual water capacity — the true water surface is typically 1–2 feet narrower once the liner and wall thickness are accounted for, and the listed gallon figure sometimes assumes a specific water level that may not match yours. If your pool has an attached spa, tanning ledge, or built-in steps, subtract roughly 5–10% from the calculated volume, since those features displace water rather than holding it. For the most accurate number, always measure your pool’s actual water dimensions rather than relying on the box label.
