How many gallons in an 18×48 pool?
An 18 ft round pool with 48 in walls, filled to 42 in, holds about 6,662 gallons. Filled to the very top it would hold 7,614 gallons.
How to work it out
- 3.1416 × (18 ft ÷ 2)² = 254 sq ft
- Water depth: 48 in wall − 6 in = 42 in
- 254.5 sq ft × 3.5 ft × 7.48 = 6,662 gal
“18 × 48” means an 18 ft round pool with 48 in walls — one of the most popular frame and steel-wall sizes. It is small enough to fill from a garden hose in a day or two, and large enough that chemical doses need real measuring.
Adjust for your project
- Gallons if filled to the top of the wall
- 7,614 gal
- Water depth
- 42 in
- Water surface
- 254 sq ft
- Water in each inch of level
- 159 gal
18 ft round pool by water depth
| Water depth | Gallons at your water level |
|---|---|
| 38 in | 6,028 gal |
| 40 in | 6,345 gal |
| 42 in | 6,662 gal |
| 44 in | 6,980 gal |
| 46 in | 7,297 gal |
| 48 in | 7,614 gal |
An 18×48 in numbers
The water surface is about 254 sq ft, so each inch of water is about 159 gallons. At the usual fill line (around 42 in) that is roughly 6,700 gallons; at 44 in it is about 6,980 — close to what some frame-pool makers list for their 18 ft pools.
- Chemicals. At about 6,700 gallons, a label rate “per 10,000 gallons” is roughly two-thirds. Raising chlorine 3 ppm takes about 20 fl oz of 12.5% liquid chlorine.
- Salt. From fresh water to 3,200 ppm is about 178 lb — four and a half 40 lb bags.
- Filter. Turning 6,700 gallons over in 8 hours needs about 14 gpm; the sand-filter pumps sold with these pools are sized for that range.
- Fill time. At about 7.5 gpm from a hose, roughly 15 hours.
For a 52 in wall the same diameter holds about 7,300 gallons at 46 in. Neighbouring sizes: how many gallons in a 15x48 pool and how many gallons in a 21 ft round pool. For the base: how much sand for an 18 ft above-ground pool.
Different size? Use the full Above-Ground Pool Gallons Calculator.
What you’ll need
- Pool test stripsBudget price
Quick daily checks. Fine for spotting a trend; use a drop kit when you’re about to add a big dose or shock.
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) - Floating chlorine dispenserBudget price
Holds 3-inch tablets with an adjustable vent. Keep it away from skimmers, ladders and vinyl it can rest against.
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 in an 18×52 pool?
About 7,297 gallons filled to 46 in, 6 in below the top of a 52 in wall.
How many gallons in an 18 ft round pool 4 ft deep?
About 7,614 gallons with a full 48 in of water.
Other common sizes
- How many gallons in a 24 ft round pool — 12,972 gal
- How many gallons in a 15x48 pool — 4,627 gal
- How many gallons in a 12x30 pool — 1,904 gal
- How many gallons in a 21 ft round pool — 9,932 gal
- How many gallons in a 27 ft round pool — 16,418 gal
- How many gallons in a 15x30 oval pool — 11,519 gal
- How many gallons in an 18x33 oval pool — 15,039 gal
Sources
- NIST Handbook 44, Appendix C — General tables of units of measurement (opens in a new tab) — 1 US gallon = 231 cubic inches (7.48052 gallons per cubic foot).
- Intex — Ultra XTR Frame 24 ft × 52 in pool (product page) (opens in a new tab) — Lists a water capacity of 12,481 gallons for a 24 ft × 52 in pool; the fill depth is not stated.
- Intex — Ultra XTR Frame 18 ft × 52 in pool (product page) (opens in a new tab) — Lists 6,981 gallons.
- Intex — Ultra XTR Frame 16 ft × 48 in pool (product page) (opens in a new tab) — Lists “5,061 gallons (90%)” — capacity at 90% of the wall height.