Pool Volume Calculator

This pool volume calculator will let you know the amount of water you will need to fill a number of different size/depth pools. It can also give you an estimate of how much the water you use will cost.


Select your pool shape. You can choose between seven different shapes.

Input your swimming pool's dimensions, using feet and inches.

Click on the "Calculate" button and you will be given the volume of water your pool requires.

Additionally, if you know what is charged for water in your neighborhood, you can work out how much filling your pool will cost. Input the charge per gallon for water and choose your local currency from the drop-down menu. This calculator will then give you the total cost of filling your pool, based on the information you've given.

Swimming Pool Volume Calculator

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Rectangular and Square Pools

If your pool is rectangular or square and the same depth throughout, it's a simple matter to measure it. All we need to do is multiply width by length by depth. However, most pools are irregularly shaped and/or have depth changes. To calculate water volume for rectangular or square pools with a varied depth, you need to multiply width by length by the average depth. You can calculate the average depth by adding the deep end depth and the shallow end depth together and halving the result.

Bear in mind that pools are not usually filled up right to the edge; for the purposes of your calculations, use the actual depth of the water, not the depth of the pool's sides.

Round, Kidney and Irregular Pools

If you need to calculate the volume for a round/circular pool, find the square of the radius (i.e., multiply the radius by the radius). Multiply your answer by the pool's average depth, and multiply that result by Pi (3.141592654).

The simplest way to work out the volume of your pool is to imagine it as being made up of a pair of smaller shapes. You can take measurements for both the shapes, and by adding them you will get the total volume of your pool. Use the appropriate formula from the ones above to calculate the volume of each part of your pool.

Firstly, add the two shapes' total measurements together. Now multiply that number by 0.45, and multiply the result by your pool's length, and this will give you your pool's total surface area. Lastly, multiply the surface area by your pool's average depth (using the formula above) and this will give you the volume in cubic feet.

Imagine your pool is kidney-shaped, one section having a 25 foot circumference and the other section having a 15 foot circumference, with a length of 50 feet and a depth of 6 feet. The calculation you would make would be as follows: 0.45 × (25 + 15) × 50 × 6 = 5400 cubic feet.

Converting to Gallons

It's essential to know your pool's total volume of water so that you can get the amount of chemicals it needs correct. This is a simple calculation once you've worked out the volume of your pool in cubic feet. One cubic foot of water equals 7.48 US gallons; once you have calculated the volume of your pool in cubic feet, simply multiply it by 7.48 and the answer is the number of gallons of water your pool holds.


The pool volume calculator uses the following formulas:

  • Square: Volume (US Gallons) = Side Length2 × Average Depth × 7.48
  • Rectangle: Volume (US Gallons) = Length × Width × Average Depth × 7.48
  • Kidney: Volume (US Gallons) = 0.45 × (Width A + Width B) × Length C × Average Depth × 7.48
  • Round: Volume (US Gallons) = Pi × Radius 2 × Average Depth × 7.48
  • Trapezoid: Volume (US Gallons) = ((a + b) / 2 ) × h × Average Depth × 7.48
  • Triangle: Volume (US Gallons) = (1/4) × [ (a+b+c) × (b+c-a) × (c+a-b) × (a+b-c) ] 0.5 × Average Depth × 7.48
  • Oval: Volume (US Gallons) = Pi × r × R × Average Depth × 7.48
  • Where: Pi = 3.141592654, Average Depth = (depth at deep end + depth at shallow end) / 2

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