Intex Pool Calculator
Find how much water an above-ground pool holds — round, oval or rectangular — plus fill time with a garden hose, how long the filter pump takes to circulate it, and what the water weighs. Works for Intex frame and inflatable pools and any other pool of the same shape.
How the volume is calculated
All measurements are in feet before multiplying, so a water depth of 3 ft 6 in is entered as 3 feet and 6 inches and converted to 3.5 ft.
Worked example: a 15 ft round pool
With water 36 inches deep, the radius is 7.5 ft, so the volume is 3.14159 × 7.5² × 3 = 530 cubic feet, or about 3,966 US gallons (15,012 litres).
- Filling from a hose delivering 8 gallons a minute takes about 8 hours 16 minutes.
- A 1,000 gallon-per-hour filter pump moves the full volume once in about 4 hours.
- The water weighs roughly 33,000 lb, about 16.5 US tons.
Measure the water, not the box
The size printed on a pool box is usually the outside size. Frame and inflatable walls take up space, so measure across the inside of the wall for the most accurate figure.
Depth matters even more. Pools are not filled to the top of the wall, so a pool sold as 48 inches tall may hold water 40 to 44 inches deep. Measure the actual water depth with a tape. Each inch of depth on a 15 ft round pool is about 110 gallons.
Approximate volumes for common round sizes
| Diameter | Water depth | US gallons | Litres |
|---|---|---|---|
| 8 ft | 24 in | 752 | 2,847 |
| 10 ft | 26 in | 1,273 | 4,819 |
| 12 ft | 27 in | 1,904 | 7,206 |
| 15 ft | 36 in | 3,966 | 15,012 |
| 18 ft | 45 in | 7,138 | 27,022 |
These are calculated from the diameter and water depth shown, not taken from any manufacturer's specification. Your own pool will differ if the inside diameter or water level is different.
Using the gallons for chemicals
Pool chemical labels usually give a dose per 10,000 gallons. Divide your gallons by 10,000 and multiply the label dose by the result: a 3,966-gallon pool needs about 0.4 of the per-10,000-gallon dose. Always follow the product label, add chemicals gradually, and test the water before adding more.
Pump run time
A common rule of thumb is to circulate the full volume of water at least once a day. The turnover figure above shows how long one full circulation takes at the pump's rated flow. Real flow is often lower than the rating once the filter starts to load up, so many owners run the pump longer than the minimum.
Why the weight matters
Water weighs about 8.34 lb per US gallon, so even a modest pool weighs many tons. Set it on level, compacted ground. A slope or soft patch lets the water shift toward one side, which strains the wall and can cause a collapse. Above-ground pools should not be placed on a deck or balcony unless it has been engineered for that load.
This calculator is an independent tool and is not affiliated with or endorsed by Intex.
Frequently Asked Questions
Multiply 3.14159 by the radius squared and by the water depth, all in feet, then multiply by 7.48052. A 15 ft round pool with 36 inches of water holds about 3,966 gallons. Use the inside diameter and the actual water depth, not the size printed on the box.
Divide the pool volume in gallons by the hose flow in gallons per minute. A typical garden hose delivers somewhere around 5 to 10 gallons per minute, so a 4,000-gallon pool takes roughly 7 to 13 hours. You can measure your own hose by timing how long it takes to fill a 5-gallon bucket.
A common rule of thumb is long enough to circulate the whole volume at least once a day. Divide the pool volume by the pump flow in gallons per hour to get the time for one turnover, then allow extra time because real flow drops as the filter loads.
About 8.34 lb per US gallon. A 4,000-gallon pool holds over 33,000 lb of water, which is why it must sit on level, compacted ground.