How many gallons is a 20 ft round pool?
A 20 ft round pool holds about 8,000 to 9,200 gallons.
On this page (7 sections)
Intex rates the Ultra XTR Frame 20 ft × 48 in at 7,947 gallons, and geometry at 90% fill gives 8,460 gallons for a 48 in wall and 9,165 for a 52 in wall.
Quick answer: 20 ft round pool gallons by wall height
For a "20x52" pool, geometry gives 9,165 gallons, and our frame-pool estimate is 8,524. For a 54 in wall, the estimate is 8,852. The table below shows all four common wall heights with both the geometric and the corrected numbers, plus the one 20 ft model in our database.
| Wall height | Geometry | Frame pool estimate (× 0.93) | Inflatable estimate (× 0.87) |
|---|---|---|---|
| 42 in wall | 7,403 gal28,022 L | 6,885 gal | 6,440 gal |
| 48 in wall | 8,460 gal32,026 L | 7,868 gal | 7,360 gal |
| 52 in wall | 9,165 gal34,694 L | 8,524 gal | 7,974 gal |
| 54 in wall | 9,518 gal36,029 L | 8,852 gal | 8,280 gal |
Geometry = π/4 × diameter² × water depth × 7.48. Real pools hold less than the nominal size suggests. The factors are medians of 26 manufacturer capacities (our own calculation).
| Model | Capacity | Fill basis | Real ÷ nominal geometry | Source |
|---|---|---|---|---|
| Intex Ultra XTR Frame 20ft x 48in | 7,947 gal30,083 L | not stated | 0.939 | manufacturer |
| Change | Amount |
|---|---|
| +1 ppm FC (12.5% liquid chlorine) | 8.1 fl oz238 mL |
| +10 ppm TA (baking soda) | 1.1 lb500 g |
| +10 ppm CYA (stabilizer) | 10.5 oz298 g |
Closest full chart: 8,000 gal dose chart.
Always follow your product’s label directions. Pool and spa chlorine, bromine, shock and algaecides are EPA-registered pesticides: use products labeled for pool or spa use, and don’t swim or soak until levels are within the limit on your product’s label. If this page and a label disagree, the label wins.
Manufacturer capacities for this size
Intex's page for the Ultra XTR Frame 20 × 48 gives 7,947 gallons but doesn't state the fill level. Compared with the geometric volume for a 48 in wall at 90% fill, that is a ratio of 0.939. This matches the frame pools that do state 90%, so 90% is the likely basis, but we could not confirm it. If you own a 20 ft steel-wall pool from another manufacturer, use the capacity in your manual. Without it, the calculator's frame estimate is usually within about ±7%.
Why does 7% matter? At this size, 7% is about 560 gallons. Over a season of daily chlorine, that means you add too much or too little every day. It's also why your test readings, not the volume math, should decide your doses.
Starting doses for this volume
- Chlorine, +1 ppm (7,947 gal): 8.1 fl oz of 12.5% liquid chlorine, 10 fl oz of 10%, or 16 fl oz of 6% bleach.
- Chlorine, +1 ppm (52 in wall, 8,524 gal estimate): 8.7 fl oz of 12.5%.
- Alkalinity, +10 ppm: 1.1 lb of baking soda (7,947 gal).
- Stabilizer (CYA) on a fresh fill: 2.0 lb for 0 to 30 ppm; 2.65 lb for 0 to 40 ppm.
- Salt for a new salt system: about 212 lb to 3,200 ppm, five 40 lb bags plus 12 lb.
Always follow the product label. It is a violation of federal law to use a pesticide product in a manner inconsistent with its labeling. The 8,000-gallon dose chart is the closest full chart. For a 52 or 54 in wall, also check the 10,000-gallon chart and scale by your volume.
Calculator: your exact depth
Set 20 ft, your wall height, and your fill level. The water in a 48 in pool at 90% fill is about 43 in deep. If your water level is lower or higher, enter your measured depth.
Chemicals per week for this size (estimate from your own loss)
For 7,947 gallons, each ppm of daily loss costs about 57 fl oz of 12.5% liquid chlorine a week. A 1.5 ppm daily loss is 85 fl oz a week. A 2 ppm daily loss is 114 fl oz, nearly a full gallon jug. If that sounds like a lot to carry, compare costs per ppm, not per jug, in the chemical cost calculator. Tablets in a floater are an option too, but they add stabilizer every week, which raises the chlorine level your pool needs.
The water itself weighs about 66,000 lb (7,947 gallons × 8.34 lb per gallon), which is why above-ground pools this size need firm, level ground.
Safety. Add chlorine and pH chemicals separately, at least 30 minutes apart, with the pump running. Never mix chlorine products with each other or with acid. Poison Control: 1-800-222-1222.
FAQ
How many gallons is a 20x52 above ground pool?
Geometry at 90% fill gives 9,165 gallons. Frame pools usually hold a bit less. Our estimate is 8,524 gallons. Use your model's rated capacity if the manual lists one.
How much chlorine for a 20 ft pool?
About 8.1 fl oz of 12.5% liquid chlorine per 1 ppm in a 48 in pool (7,947 gallons) and 8.7 fl oz in a 52 in pool. A 3 ppm top-up is 24–26 fl oz.
How long does it take to fill a 20 ft pool?
For 7,947 gallons: about 26.5 hours at 5 gallons per minute, or 13.2 hours at 10. For each $1 per 1,000 gallons on your water bill, the fill costs about $7.95.
Sources
- Intex Ultra XTR Frame 20 ft × 48 in, read 2026-09-29: intexcorp.com
- Weight of water, 8.34 lb per gallon: USGS Water Science School
- Volume formulas, correction factors, and dose math: methodology