How many gallons per inch in a 24 ft round pool?
Each inch of water in a 24 ft round pool is about 282 gallons. The surface is 3.1416 × 12² = 452 square feet, and every square foot holds 0.623 gallons per inch.
How to work it out
- Surface: 3.1416 × (24 ft ÷ 2)² = 452 sq ft
- Per inch: 452 sq ft × 0.623 gal = 282 gal
- Loss: 1 in a week (0.14 in a day) → 40 gal a day × 7 = 282 gal a week; × 365 days = 14,705 gal
- Heat: 40 gal × 8.34 lb × 1,048 Btu = 352,121 Btu a day (103 kWh)
- Cover: 90% of evaporation prevented = 13,234 gal a year, $66.17
Gallons per inch is the most useful number an above-ground pool owner can know. It turns “the water’s down two inches” into a volume you can price, dose for or drain — and on a round pool it depends only on the diameter, not on the wall height.
Adjust for your project
- Gallons in each inch of level
- 282 gal
- Per day
- 40 gal
- Per month (30 days)
- 1,209 gal
- Per year (days above)
- 14,705 gal
- Level drop
- 1 in a week (0.14 in a day)
- Heat carried off by evaporation
- 352,121 Btu a day (103 kWh)
- Top-up water cost a year
- $73.52
- Water a cover saves a year
- 13,234 gal
- Cover saving a year (water only)
- $66.17
- Evaporation also takes heat: DOE says each pound of 80°F water that evaporates carries off 1,048 Btu, which is why a cover saves heating as well as water. Splash-out and backwashing add to the top-ups but not to the heat loss.
24 ft round pool: water lost by level drop
| Drop a week | Water lost a week | Per year (days above) | Water a cover saves a year |
|---|---|---|---|
| 0.25 in | 71 gal | 3,676 gal | 3,309 gal |
| 0.5 in | 141 gal | 7,352 gal | 6,617 gal |
| 1 in | 282 gal | 14,705 gal | 13,234 gal |
| 1.5 in | 423 gal | 22,057 gal | 19,851 gal |
| 2 in | 564 gal | 29,410 gal | 26,469 gal |
| 3 in | 846 gal | 44,114 gal | 39,703 gal |
Using the 282-gallon inch
- Top-ups. A 1 in drop over a week is about 282 gallons to put back — roughly 38 minutes on a hose that fills a 5-gallon bucket in 40 seconds.
- Evaporation over a summer. At an example 1 in a week, that is about 14,700 gallons a year if it went on all year: more than the whole pool holds. A cover that stops 90% of it, by SNWA’s figure, keeps around 13,200 gallons of that in the pool.
- Lowering for winter. Dropping the level 6 in below the skimmer before closing drains about 1,700 gallons.
- Diluting stabilizer. Draining 12 in and refilling replaces about 3,380 gallons, roughly a quarter of a 13,000-gallon pool — about a quarter off the CYA. The pool drain and refill calculator works out how far to go.
- Heat. Each inch that evaporates from 80°F water carries off about 2.5 million Btu, by DOE’s 1,048 Btu per pound.
Other round pool sizes
Because the area grows with the square of the diameter, a 27 ft round holds about 357 gallons per inch and an 18 ft round about 159; the variants below work them out. The pool’s total volume is on how many gallons in a 24 ft round, 52 in pool, and the fill time on how long it takes to fill a 24 ft round pool.
Different size? Use the full Pool Evaporation & Water Loss Calculator.
What you’ll need
- Solar cover (bubble cover)Mid-range price
The cheapest heating upgrade there is: cuts evaporation and holds heat in overnight. Buy the size up and trim it.
See options on Amazon (opens in a new tab) - Hose water flow meterBudget price
Screws onto the hose and counts gallons, so you know exactly how much went in — and your real fill rate.
See options on Amazon (opens in a new tab) - Above-ground pool linerPremium price
Bought by pool size, shape and wall height. Check overlap vs beaded vs J-hook before ordering.
See options on Amazon (opens in a new tab)
As an Amazon Associate we earn from qualifying purchases. Links to products are affiliate links — they cost you nothing extra and help keep these calculators free.
Frequently asked questions
How many gallons per inch in an 18 ft round pool?
About 159 gallons per inch, from 254 square feet of surface.
How many gallons per inch in a 27 ft round pool?
About 357 gallons per inch, from 573 square feet of surface.
How much does a 24 ft round pool lose to evaporation in a week?
At an example rate of 1 inch a week, about 282 gallons, and the evaporation carries off 352,121 Btu a day (103 kWh).
Sources
- Southern Nevada Water Authority — Pools and spas (opens in a new tab) — The average in-ground pool loses 48.6 gallons of water per square foot per year to evaporation (Las Vegas); a 470 sq ft pool loses about 22,842 gallons a year; pool covers reduce evaporation by 90 percent; the four-step bucket test.
- Southern Nevada Water Authority — Water leaks (opens in a new tab) — Bucket test to tell evaporation from a pool leak.
- US EPA WaterSense — Pool water efficiency (opens in a new tab) — Using a pool cover can prevent up to 95 percent of pool water evaporation.
- US DOE Energy Saver — Swimming pool covers (archived) (opens in a new tab) — Evaporation is by far the largest source of energy loss; each pound of 80°F water that evaporates takes 1,048 Btu of heat out of the pool; covers reduce make-up water 30%–50%.
- NIST Handbook 44, Appendix C — General tables of units of measurement (opens in a new tab) — 1 US gallon = 231 cubic inches, so 1 inch over 1 sq ft = 144 ÷ 231 = 0.623 gallons.