To calculate the gallons you also need the average depth. Then you take lenth X width X average depth = cubic feet of water. cubic feet of water X 7.48 {gallons per cubic foot} = total gallons.
300 gallons.
This pool can hold a maximum of about 5,707.6 gallons of water.
Is the pool a circle? Do you want US gallons, or Imperial gallons?
An 18-foot round pool with 3 feet of water contains 5,734.8 gallons of water. If you fill it to 4 feet deep it increases to 7,646 gallons of water.
If filled to the top, there would be approx. 7400 gallons of water in your pool.
About 7,600 gallons
17,820 gallons. More pool questions answered at bridgecitypools.com
If this is a round pool 18 feet across and you fill it with 4 feet of water, it contains 7,646 gallons of water.
359 gallons for every inch the water is deep.
432 gallons.
If that is 4 feet tall and 18 inches in diameter, it would be 16.83 gallons.
(18 x 48) / 7.48=115.5