Just a little over 6,000 gallons.
8000 Gallons -- ANSWER -- For every foot of water in the pool there is 1,585 imperial gallons.
If it is a round 18' in diameter and a constant 52" deep then the volume is 158.6 gallons per inch. 52 inches would then be 8247.2 gallons.
Well my pool is 14' round an 36" deep an it took 2200 gallons so your probably looking at around 5000 gallons.
If it is 4 feet deep, then 13,500 gallons
24' x 4' round above ground holds 14,000 gallons
An 18' Round 52" wall above ground pool holds approximately 7300 gallons
13,346 gallons per vertical foot.
Your round pool has a volume of 2463 cubic ft. The formula to achieve this is Pi * (radius squared) * depth of 4 ft. Converting this to U.S. Gallons comes to 18,425 gallons.
Apx 18420 gal. in a 28 round 4ft pool
You'd need 8,602.2 gallons of water to fill this pool to the very top.
To calculate this the depth would also be needed
2977 (us) gallons Filled to the brim probably closer to 2500 for normal fill level
I have a 12' above ground round pool that is fillable up to about 29 inches and it holds roughly about 1600 gallons so yours will probably hold more than 2000 gallons.