If the bottom is flat and level, then it takes 239.38 gallons for each inch of the water's depth.
13,500 gallons
The pool holds 7,600 gallons of water
If you fill it with 4 feet of water (48 inches), the pool will contain about 5,310 gallons of water.
21,205.75 gallons
13,009.5 gallons.
6,041.6 gallons.
A 12-foot round pool filled with 3 feet of water contains 2,549 gallons water. If you fill it to 4 feet deep it changes to about 3,400 gallons.
Twelve feet of water in a 10-foot round pool is approximately 7,080 gallons.
Exactly 5264.1669 gallons
Go to http://www.havuz.org/pool-calculators.htm
To fill it to the top you will need 9,558 gallons of water.
Based on my calculations, there are 588 gallons per foot of water height in a 10 foot pool. If you have the same pool I have, it is about 3 feet high. This pool has 1,764 gallons.