A 21' pool that is 48" high should have 10,407 gallons of water (approx). To calculate the gallons in a round swimming pool use this formula: Length x length x average depth x 5.9 = gallons of pool So in your case 21 x 21 x 4 x 5.9 = 10,407 gallons
8000 Gallons -- ANSWER -- For every foot of water in the pool there is 1,585 imperial gallons.
9,440 gallons.
1.74 gallons
A round pool that is 16 feet across and is filled with 48 inches of water will contain about 6,041 gallons of water.
6015.77 gallons
15000 gallons
18,000
13,346 gallons per vertical foot.
Just a little over 6,000 gallons.
If it is 4 feet deep, then 13,500 gallons
24' x 4' round above ground holds 14,000 gallons
To calculate this the depth would also be needed