Pool volume calculator: how many gallons is my pool?
18,193 gallons
512 sq ft of surface × 4.75 ft average depth = 2,432 cubic feet · 7.48 gallons per cubic foot (231 cubic inches each) · for a 16 × 32 ft pool, 3.5 to 6 ft deep
Run your own numbers
Enter it the way you measured it: 4.5, 4 1/2,
3/8 or 10' 6".
18,193 gallons
512 sq ft of surface × 4.75 ft average depth = 2,432 cubic feet · 7.48 gallons per cubic foot (231 cubic inches each)
Source: NIST Handbook 44-2026, Appendix C, General Tables of Units of Measurement: 1 gallon = 231 cubic inches (National Institute of Standards and Technology), read November 3, 2026. Data sheet (PDF)
A 16 by 32 foot pool that runs from 3 1/2 to 6 feet deep holds 18,193 gallons: 512 square feet times a 4.75 foot average depth is 2,432 cubic feet, at 7.48 gallons each.
A worked example
An oval above ground pool of 15 × 30 ft with water 4 ft 3 in deep needs 12,771 gallons. The oval is a 15 × 15 ft rectangle with two half circles of 15 ft: 225 + 176.7 = 401.7 sq ft. Times 4.25 ft of water, 1,707 cubic feet, and times 1,728 ÷ 231, 12,771 gallons. Treated as a plain rectangle it would be 14,306, 1,535 gallons too many.
How many gallons in a 24 ft round pool?
About 13,536 gallons with 4 ft of water: 452.4 sq ft of surface × 4 ft = 1,809.6 cubic feet, at 7.48 gallons each. With 4 ft 4 in of water, 14,664 gallons.
How do you work out pool volume in gallons?
Surface in square feet × average depth in feet = cubic feet; cubic feet × 1,728 ÷ 231 = gallons, because a U.S. gallon is 231 cubic inches exactly (NIST Handbook 44). That is 7.48 gallons per cubic foot.
What else it is called
Also searched as a pool gallon calculator, how many gallons in my pool or pool size in gallons. Measure the water depth, not the height of the wall. The gallons go straight into the pool salt calculator.
Gallons by pool size
| Pool | Water surface | Gallons |
|---|---|---|
| Rectangle 12 × 24 ft, 3 1/2 to 6 ft deep | 288 sq ft | 10,233 |
| Rectangle 14 × 28 ft, 3 1/2 to 6 ft deep | 392 sq ft | 13,929 |
| Rectangle 16 × 32 ft, 3 1/2 to 6 ft deep | 512 sq ft | 18,193 |
| Rectangle 18 × 36 ft, 3 1/2 to 6 ft deep | 648 sq ft | 23,025 |
| Rectangle 20 × 40 ft, 3 1/2 to 6 ft deep | 800 sq ft | 28,426 |
| Round 12 ft, 4 ft of water | 113 sq ft | 3,384 |
| Round 15 ft, 4 ft of water | 177 sq ft | 5,288 |
| Round 18 ft, 4 ft of water | 254 sq ft | 7,614 |
| Round 21 ft, 4 ft of water | 346 sq ft | 10,364 |
| Round 24 ft, 4 ft of water | 452 sq ft | 13,536 |
| Round 27 ft, 4 ft of water | 573 sq ft | 17,132 |
| Round 30 ft, 4 ft of water | 707 sq ft | 21,151 |
| Oval 12 × 24 ft, 4 ft of water | 257 sq ft | 7,693 |
| Oval 15 × 30 ft, 4 ft of water | 402 sq ft | 12,020 |
| Oval 18 × 33 ft, 4 ft of water | 524 sq ft | 15,693 |
Gallons = cubic feet × 1,728 ÷ 231: a U.S. gallon is 231 cubic inches exactly (NIST Handbook 44-2026, Appendix C), 7.48 gallons per cubic foot. Depth is the average of the shallow and the deep end; an oval here has straight sides and round ends, like above ground oval pools.
Where the numbers come from
- NIST Handbook 44-2026, Appendix C: “4 quarts = 1 gallon (gal) = 231 cubic inches”, “1 728 cubic inches (in3) = 1 cubic foot (ft3)” and, in the liquid volume table, 1 cubic foot = 7.480 519 gallons. Read November 3, 2026. NIST Handbook 44 (PDF)
- Water surface: rectangle, length × width; round, π ÷ 4 × diameter²; oval with straight sides and round ends, (length − width) × width + π ÷ 4 × width². Depth: the average of the shallow and the deep end, exact for a floor that slopes evenly from one to the other.
Kidney and free form pools have no single formula: measure them as rectangles and circles that add up to the outline and add the gallons. A pool with a hopper or a sudden drop to the deep end holds more than the average of the two depths.
By Javier Miralles · Last updated . How this site is made.
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