12 x 12 x 3 x 5.9 = 2548 gallons
A 100-foot round pool filled with 1.5 feet of water would be holding about 88,500 gallons.
If 20' is the circumference, then the answer is 833.4 gallons.
A 28-foot round pool filled with 4 feet of water would contain about 18,500 gallons.
how many ounces do of roundup do I mix with two gallons of water?
Volume is two dimensional and no area can hold 25 gallons of water, however 25 gallons is a volume. Do you mean what dimensions would hold 25 gallons?
you would need to know the height of the pool too.
If you filled it all the way to the top (40") it would hold about 2,830 gallons of water.
9,510.19 Gallons
It depends on how deep the water is. Since it's a fairly small pool, let's say you fill it to 1 foot deep. In that case the total volume will be about 262 gallons of water. If you went to 1.5 feet the gallons would be about 392 gallons and if you filled the pool to 2 feet, the gallons would increase to about 523 gallons.
If that is 4 feet tall and 18 inches in diameter, it would be 16.83 gallons.
If you filled it all the way to the top it would be holding about 15,594 gallons of water. If you filled it to three feet deep, it decreases to around 10,200 gallons.
196 cubic feet is the volume of your pool. Converted to U.S. gallons would be, drum roll please...1,469 gallons.