Calculate the Size of a Swimming Pool

It is important to know how many gallons of water are in your swimming pool for many reasons. Two of the most important reasons would be for proper equipment sizing and maintaining the proper chemical balance in the water. Below we have provided a few charts to assist you in estimating how many gallons of water are in your swimming pool, spa, or water feature.  Using these charts will assist you in determining the quantity of chemicals you can safely add to your swimming pool in order to keep it in balance. These charts also provide you with the basic information you need to begin to calculate the gallons per minute and turnover rate your project requires for proper filtration, heating, and sanitation requirements.  

Gallons of water per average depth

Pool Size 3.5’ Average Depth 4’ Average Depth 4.5’ Average Depth 5’ Average Depth
12‘x24’ 7,600 gal 8,600 gal 9,700 gal 10,800 gal
15‘x30’ 11,800 gal 13,500 gal 15,200 gal 16,900 gal
18‘x36’ 17,000 gal 21,900 gal 24,300 gal 26,700 gal
20‘x40’ 21,000 gal 24,000 gal 27,000 gal 30,000 gal
25‘x45’ 29,531 gal 33,750 gal 37,968 gal 42,187 gal
30‘x50’ 39,375 gal 45,000 gal 50,625 gal 56,250 gal

Weight of water per average depth

Pool Size 3.5’ Average Depth 4’ Average Depth 4.5’ Average Depth 5’ Average Depth
12‘x24’ 56,848 lbs 64,328 lbs 72,556 lbs 80,784 lbs
15‘x30’ 88,264 lbs 100,980 lbs 113,696 lbs 126,412 lbs
18‘x36’ 127,160 lbs 163,812 lbs 191,484 lbs 199,716 lbs
20‘x40’ 157,080 lbs 179,520 lbs 201,960 lbs 224,400 lbs
25‘x45’ 220,892 lbs 252,450 lbs 284,000 lbs 315,558 lbs
30‘x50’ 294,525 lbs 336,600 lbs 378,675 lbs 420,750 lbs