Calculating Pool Volume


Knowing how many gallons of water your pool holds is essential to properly balancing your water. Rough estimations can be made, but errors can end up causing issues. Over estimate how many gallons you have and you could end up spending more money than you need to and end up adjusting your chemistry too much. On the other hand, if you under estimate, you will end up having to reapply your treatment at another time in order to properly balance the water.

Sometimes, owners are not aware of how many gallons their pool is. If the amount is not in the original documentation that came with the pool, it is simple to calculate an approximate amount by yourself.

You will need three measurements from your pool for this formula: average length, average width, and average depth.

There are more specific, but also more complicated, formulas for measuring volume on oddly shaped pools, so for now we’ll just focus on the basic one. The other formulas can be found in Chapter 3 of Leslie’s Pool Care Guide.

After recording your measurements mentioned above, take each number and multiply it by one another. This result will then be multiplied by 7.5 (approximately how many gallons are in a cubic foot).

The combined formula should look like this:

L × W × D × 7.5 = Total gallons in pool

Once you have this number, you should be able to accurately apply the correct amount of chemicals to your pool and avoid any future dosage issues.


For more information on pool size or chemical usage, visit or reach out to one of our knowledgeable staff members at your local Leslie’s Store.