How Do I Calculate The Volume Of Water In My Pool?

Matt Makuch
Mar 25
3 min read

If you own a swimming pool, knowing its water volume is essential for proper maintenance, chemical balancing, and even when ordering water deliveries. Whether you’re filling your pool for the first time or performing routine maintenance, accurately calculating your pool's volume ensures efficiency and cost savings.

At Fortin Water, we specialize in delivering high-quality pool water across New Hampshire (NH) and Massachusetts (MA). In this guide, we’ll walk you through simple formulas to determine your pool’s water volume, no matter the shape. We’ll also discuss why accurate calculations matter, common mistakes to avoid, and tools that can help simplify the process.

Why Knowing Your Pool’s Water Volume Matters

Understanding how much water your pool holds is crucial for several reasons:

1. Accurate Chemical Treatment

Adding too much or too little chlorine, algaecides, or pH balancers can lead to water that is either unsafe or ineffective in preventing bacteria and algae growth. A precise water volume measurement helps maintain the right balance for a clean and safe swimming experience.

2. Water Conservation and Cost Management

Overfilling your pool wastes water and increases your utility bills. Proper volume calculation helps you fill the pool efficiently while minimizing water waste. If you rely on a water delivery service like Fortin Water, knowing your pool’s exact volume prevents over-ordering or under-ordering water.

3. Pool Equipment Sizing

Your pool pump, filter, and heater must be appropriately sized to work efficiently. A pump that’s too small won’t circulate water effectively, while an oversized heater may lead to excessive energy use. Knowing your pool volume ensures you select the right equipment.

4. Seasonal Pool Maintenance

During winterization or when preparing your pool for summer, understanding its volume helps ensure proper draining, refilling, and chemical treatment adjustments.

How to Calculate the Volume of Water in My Pool

Step 1: Determine Your Pool Shape

Different pool shapes require different formulas for calculating volume. Identify which category your pool falls under:

Rectangular or Square Pools
Circular Pools
Oval Pools
Irregular-Shaped Pools

Step 2: Use the Correct Pool Volume Formula

Rectangular or Square Pools

Formula:

Volume(in gallons) = Length(ft) X Width(ft) X Average Depth(ft) X 7.5

Example:

If your pool is 30 feet long, 15 feet wide, and has an average depth of 5 feet:

30 X 15 X 5 X 7.5 = 16875 gallons

Circular Pools

Formula:

Volume(in gallons) = Radius(ft) X Radius(ft) X Depth(ft) X 3.14 X 7.5

Example:

A circular pool with a 10-foot radius and 4-foot depth:

10 X 10 X 4 X 3.14 X 7.5 = 9420 gallons

Irregular-Shaped Pools

For freeform pools, divide the pool into multiple sections (rectangles, circles, etc.), calculate each section’s volume separately, and sum the results.

Step 3: Adjust for Sloped Pools

If your pool has a deep and shallow end, find the average depth using:

(Shallow End Depth X Deep End Depth) / 2

For example, if your shallow end is 3 feet and your deep end is 7 feet:

( 3 + 7 ) / 2 = 5 feet average depth

Common Mistakes When Calculating Pool Volume

1. Incorrect Depth Measurement

Many pool owners forget to factor in slopes or irregular depths. Always calculate an average depth to avoid miscalculations.

2. Rounding Errors

Precision matters, especially for larger pools. Small miscalculations can lead to significant errors in water treatment and filling estimates.

3. Ignoring Pool Features

Steps, built-in seating, and tanning ledges displace water, reducing your pool’s actual volume. Account for these features when estimating total water capacity.

4. Forgetting to Adjust for Water Levels

Most pools are not filled to the very top. If you typically leave a few inches below the edge, adjust your calculations accordingly.

Using a Pool Water Volume Calculator

If manual calculations seem daunting, use an online pool volume calculator. Simply enter your pool’s dimensions, and it will provide an accurate volume measurement.

Some advanced calculators even allow adjustments for steps, slopes, and irregular shapes, making the process more precise.

Need a Water Delivery? Contact Fortin Water

If you’ve determined your pool’s water volume and need a fast, reliable pool water delivery in NH and MA, Fortin Water is here to help. Our 6,000-gallon tanker trucks ensure you get crystal-clear water without delays.

Call us today at (603) 622-6910 or email info@makuchindustries.com to schedule your pool water delivery!

Additional Services We Offer

Bulk water delivery for pools, ponds, and irrigation systems
Emergency water supply for construction and commercial needs
Year-round pool water delivery, even in freezing conditions
Expert guidance on pool filling and maintenance

Conclusion

Calculating your pool’s water volume is essential for maintenance, chemical balancing, and ordering the right amount of water. Whether your pool is rectangular, circular, or uniquely shaped, following these formulas will ensure accuracy.

For professional pool water delivery in New Hampshire and Massachusetts, trust Fortin Water to meet your needs with reliability and expertise.

Ready to fill your pool? Contact us today!