Pool Volume Calculator: How Many Gallons of Water Does Your Pool Hold?

Need to figure out how many gallons of water are in your pool? Just plug in your pool’s measurements into our pool volume calculator below.

Remember, before you add any chemicals to your pool water, you need to know how many gallons of water there are. Knowing your pool volume is critical for adding the correct amount of chemicals, it’s essential if you’re installing a new pool pump, pool filter, or pool heater. And keep these calculations handy for future reference. You’ll need them often as a pool owner!

Be sure to measure from the depth of your water, not the height of the wall or the depth of the pool. You want to know how much water is in your pool, and it’s probably not filled up to the top. If you have a more complicated shaped pool, you’ll need to run a few other calculations.

Pool Volume Reference Chart

You can use the pool volume reference chart below to quickly calculate the volume of these common pool sizes.

Note: These are estimates. You’ll always get more accurate results if you measure your pool yourself. And always measure the depth of your water, not the height of your wall.

How to Calculate Pool Volume Step-By-Step

If you need to calculate the volume of an irregular-shaped pool or you’re still feeling confused keep reading for a complete walk-through on these calculations.

To get your pool’s volume, you need to calculate your pool’s surface area and average depth. You’ll need a few basic metrics:

• Length (L)

• Width (W)

• Depth (D) or Height (H)

• Diameter (d) (for round pools)

• Radius (r) (for round pools)

• Pi (3.14 constant)

Multiply the length and width to get the surface area of a rectangular pool. Then throw in your pool’s depth and you’ll get basic volume calculation.

Another important part of your equation: one cubic foot of water contains 7.5 gallons. In order to figure out how many gallons your pool holds, you’ll multiply your final cubic foot measurement by 7.5 to find the volume of your pool.

Rectangular Pool Volume

How you calculate your volume will depend on how the bottom of your pool is laid out.

Constant Depth

The formula for finding the volume of a rectangular pool with one depth (no shallow or deep end) is L × W × D × 7.5 = V (in gallons).

For example, if your swimming pool is 32 feet long, 16 feet wide, and 4 feet deep:

• 32 × 16 × 4 × 7.5 = 15,360 gallons

Variable Depths with a Gradual Slope

If your rectangular pool has more than one depth (shallow end, deep end), you’ll need to do a little more math. Determine the pool’s average depth. Add the shallow end depth to the deep end depth, and divide by 2.

For example, if your pool’s shallow end is 3 feet, and the deep end is 9 feet, the average depth is 6 feet. Next, multiply your pool’s length and width and then multiply that number by the average depth. Finally, multiply that figure by 7.5 to calculate the volume of the pool in gallons.

If your pool is 32 feet long, 16 feet wide, and has an average depth of 6 feet: 32 × 16 × 6 × 7.5 = 23,040 gallons

Round or Circular Pool Volume

The formula for finding the volume in gallons of a round pool is 3.14 × r2 × D × 7.5 = V (in gallons). Start by measuring your pool’s diameter, which is measured at its widest point across (i.e. your pool’s length). Then divide the diameter by 2 to get the radius.

The radius squared is the radius multiplied by the radius. Finally, measure the pool’s depth. For example, if your pool’s diameter is 18 feet, your radius is 9 feet, and your depth is 4 feet: 3.14 × (9 x 9) × 4 x 7.5 = 7630.2 gallons

References:

Giovanisci, Matt, and Matt Giovanisci is the founder of Swim University® and has been in the pool and spa industry since 1993. Since then. “Pool Volume Calculator: How Many Gallons of Water Does Your Pool Hold?” Swim University, 19 Sept. 2023, www.swimuniversity.com/pool-calculator/. Accessed 14 Aug. 2024.