Pool Volume Calculator

Calculate how many gallons or liters of water are needed to fill a swimming pool by selecting the pool shape and size below.

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If you’re here then there’s a good chance you’re trying to find the size of your pool in gallons or trying to figure out how much water is needed to fill it. Keep reading to see the volume formulas for various pool shapes.

How to Calculate the Volume of a Rectangular Pool

Illustration showing the dimensions of a rectangular swimming pool

You can find the volume of a rectangular swimming pool in gallons by multiplying the length by the width by the average depth in feet by 7.48. The formula to find pool volume in gallons is thus:

volume = length × width × depth × 7.48.

The first part of this formula determines the volume of water in cubic feet. The second part converts cubic feet to gallons; there are 7.48 gallons of water per ft3 of water.

Most pools have varying depths that slope from shallow to deeper. To accurately find the volume of water, you’ll need to estimate the average depth. To find the average depth add the shallow depth with the deep depth, then divide by 2, e.g. (shallow + deep) ÷ 2.

How to Calculate the Volume of a Circular Pool

Illustration showing the dimensions of a circular swimming pool

You can calculate the volume of a circular swimming pool by multiplying 3.14 times the radius in feet times the radius in feet times the average depth in feet times 7.48. Thus, the formula is:

volume = πr2 × average depth × 7.48

The first part of this formula (πr2) determines the area, and multiplying by the depth finds the volume. Multiplying by 7.48 finds the gallons of water per ft3 of water.

How to Calculate the Volume of an Oval Pool

Illustration showing the dimensions of an oval swimming pool

You can calculate the volume of an oval swimming pool by multiplying the length times the width in feet times 3.14 divided by 4 times average depth in feet times 7.48. The formula is:

volume = length × width × π ÷ 4 × depth × 7.48

The first part of this formula (length × width × π ÷ 4) determines the area, and multiplying by the depth finds the volume. Again, multiplying by 7.48 determines how many gallons of water are in the pool.

Like a rectangular pool, the average depth can be found by adding the shallow and deep depths and then dividing by 2.

How to Calculate the Volume of an Irregular Oblong or Kidney Shaped Pool

Illustration showing the dimensions of an oblong swimming pool

The volume of a oblong or kidney shaped pool is a little more complicated. You can calculate its volume by multiplying the length in feet times (the shorter width in feet + the longer width in feet) times .45 times the average depth in feet times 7.48.

volume = length × (short width + the long width) × .45 × depth × 7.48

The first part (length × (short width+ long width) × .45) is used to find the area, and then the volume is found by multiplying by the depth. Like before, multiplying by 7.48 finds the number of gallons in the pool.

Weights and Measures

To find pool volume in liters you can use our gallons to liters unit conversion calculator or multiply the gallons by 3.79.

To find the weight in pounds of the water in the pool, you can multiply the number of gallons by 8.33, or use our water weight calculator.

One cubic foot of water is 12″ wide × 12″ long × 12″ deep and weighs 62.4 pounds.