Calculating Pool Size/Gallons

Knowing the number of gallons in your swimming pool is essential for maintaining the proper chemical balance.  Here are the formulas used to figure how many gallons of water your pool holds. 

Circular or Oval Pool:

Multiply the length of the pool by the width of the pool by the average depth by 5.9 = Gallons of water in pool

Example:

Deep end of the pool is 8 ft, shallow end of the pool is 3 ft :  8 + 3 ÷ 2 = 5.9 Average Depth

Length - 35 ft

Width - 20 ft 

Avg. Depth – 5.5 ft

35 x 20 x 5.5 x 5.9 = 22,715 gallons

Add approx. 500 – 600 gallons if you have a spa attached to your pool.

Square or Rectangular Pool:

Multiply the length of the pool by the width of the pool by the average depth by 7.5 = Gallons of water in pool

Example:

Deep end of the pool is 8 ft, shallow end of the pool is 4 feet: 8 + 4 ÷ 2 = 6 Average Depth

Length – 30 ft

Width – 14 ft

Avg. Depth – 6

30 x 14 x 6 x 7.5 = 18,900 gallons

Add approx. 500 – 600 gallons if you have a spa attached to the pool.