About 3,983 gallons.
A round pool with a 16-foot diameter and a 4-foot depth has a maximum capacity of about 6,016 gallons of water.
This pool can hold a maximum of about 18,420 gallons of water.
Round Pool: Depth x Diameter-squared x 5.9 = Volume in Gallons
"3 feet round" is not clearly defined: is that the radius, the diameter, or the circumference?
Depends on the depth. If it is 4 feet deep and it is cicular with a diameter of 24 feet then you have approx. 13,553 gallons of water. If it is 3 feet deep then you have approx. 10,152 gallons of water.
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.
One foot of water in a round pool with a diameter of six feet is about 211Â½ gallons.
Use this formula: Diameter x Diameter x Average Depth x 5.9 = Total Gallons
About 26,406 gallons.