Aiper AU: Pool Care

How Many Gallons Is My Pool? Free Pool Volume Calculator & Charts

Aiper

• 7 min read
An swimming pool in a tropical setting with a wooden deck and a figure-eight shape, viewed from above.

Knowing how much water your swimming pool holds is more important than most people realize. It determines chemical balance, heating needs, water replacement costs, and even how long it takes to circulate your pool properly. A pool volume calculator is the easiest way to get this number without second-guessing.

In this guide, we’ll show you:

  • Simple formulas for rectangular, round, and oval pools
  • Handy pool size charts for quick reference
  • An above ground pool size chart for common kit pools
  • Guidance for calculating irregular pool shapes
  • Recommended online pool gallon calculators
  • Smart tools to make pool care easier

By the end, you’ll be able to confidently answer the question: How many gallons is my pool?

Table of Contents

Why Pool Volume Matters

The total gallons in your pool impact every part of water care. If you underestimate, your chlorine won’t sanitize properly; if you overestimate, you’ll waste money on chemicals and energy. Knowing your exact volume helps you:

  • Add the correct dose of sanitizer, shock, or stabilizer
  • Predict water bills when refilling or topping off
  • Estimate heating costs for your system
  • Keep swimmers safe and comfortable

Accurate volume also makes pool automation more reliable. Smart cleaning and monitoring devices—like the HydroComm Smart Pool Monitor & Underwater Comm Device | Aiper—use precise water data to improve efficiency and ensure balanced water quality with less guesswork.

Pool Volume Formulas (Standard Shapes)

Although an online pool gallon calculator saves time, manual math works too. Here are the standard formulas:

Rectangular or Square Pools

Gallons = Length × Width × Average Depth × 7.5

Round Pools

Gallons = Diameter × Diameter × Average Depth × 5.9

Oval Pools

Gallons = Length × Width × Average Depth × 5.9

👉 Tip: Average depth = (Shallow end + Deep end) ÷ 2

An aerial view of a tropical swimming pool shaped like a peanut with a palm tree on a center island.

Pool Size Chart (Inground Pools)

Pool Size (ft)

Average Depth (ft)

Gallons of Water

12 × 24

5

~10,800 gallons

15 × 30

5

~16,800 gallons

18 × 36

5.5

~26,700 gallons

20 × 40

6

~36,000 gallons

This pool size chart helps owners quickly estimate volume without a calculator.

Above Ground Pool Size Chart

Above ground pools come in standard round and oval kits. Assuming ~52" wall height (≈4.3 ft water depth):

Pool Size (Round)

Average Depth

Gallons

12 ft × 52 in

4.3 ft

~3,400

15 ft × 52 in

4.3 ft

~5,300

18 ft × 52 in

4.3 ft

~7,600

24 ft × 52 in

4.3 ft

~13,600

Pool Size (Oval)

Average Depth

Gallons

12 × 24 ft

4.3 ft

~8,400

15 × 30 ft

4.3 ft

~13,000

18 × 33 ft

4.3 ft

~15,400

This above ground pool size chart gives a reliable estimate for the most popular pool packages.

A beautiful, kidney-shaped swimming pool at dusk with a person standing in the water.

Calculating Irregular Pool Shapes

Not all pools are perfect rectangles or circles. Freeform, kidney, L-shaped, or lagoon-style pools are common—and they still need accurate volume. Here’s how to calculate them:

  1. Divide into sections – Break the pool into simple shapes (rectangles, ovals, circles).
  2. Measure separately – Calculate the gallons for each section using the formulas above.
  3. Add them up – Combine the results to get total volume.
  4. Account for ledges/benches – Subtract shallow features like tanning ledges or swim-outs.
  5. Double-check depth – Freeform pools often vary more; take multiple depth readings for accuracy.

👉 Example: A kidney pool can be split into two overlapping ovals. Calculate each oval’s gallons, then subtract the overlap area.

This method won’t be 100% exact, but it usually comes within 5–10%, which is accurate enough for chemical dosing.

An aerial view of a large, irregular-shaped resort swimming pool surrounded by lush palm trees.

For quick results, try these two trusted tools:

  • Pentair Pool Volume Calculator – Pool Volume Calculator | Pool Water Calculator | Pentair is simple and accurate. Enter dimensions, choose your shape, and get an instant gallon total.
  • Trouble Free Pool Calculator – PoolMath is highly popular among pool owners. It not only calculates pool gallons but also tells you how much chlorine, stabilizer, or salt to add.

Both tools save time and reduce guesswork, especially for irregular pools or large volumes.

Smart Pool Water Monitoring

Once you know your pool’s gallon capacity, maintaining clean and balanced water becomes much easier. Manual testing can be time-consuming and prone to errors, especially in irregular or large pools.

The HydroComm Smart Pool Monitor & Underwater Comm Device | Aiper is a smart water monitoring device that lets you track your pool’s chemical levels in real time. With HydroComm, you can:

  • Monitor pH, chlorine, and other key water parameters from your smartphone app
  • Receive alerts when water chemistry is out of balance
  • Make informed decisions on dosing chemicals
  • Reduce guesswork and avoid over- or under-treating your pool

By combining accurate pool volume calculations with HydroComm’s real-time monitoring, you can ensure safe, crystal-clear water all season long—without constantly running tests manually.

smart water monitoring device that lets you track your pool’s chemical levels

How Many Gallons Is My Pool? (Examples)

  • 20 × 40 ft inground, avg depth 5 ft → 30,000 gallons
  • 15 × 30 ft inground, avg depth 6 ft → 20,000 gallons
  • 24 ft round above ground, 52" depth → 13,600 gallons

Final Thoughts

Knowing your pool’s capacity is the foundation of safe and cost-effective maintenance. Whether you use a formula, check a pool size chart, or rely on an online pool gallon calculator, the result helps you balance water correctly and save money.

For simple shapes, the math is easy. For complex pools, break the design into sections—or use Pentair or TFP calculators. And for ongoing water quality management, the HydroComm Smart Pool Monitor & Underwater Comm Device | Aiper lets you monitor your pool from anywhere via its app, giving you precise, real-time insight into pH, chlorine, and other key parameters.

With the right combination of volume calculation and smart water monitoring, you’ll always know “How many gallons is my pool?” and whether your water chemistry is perfectly balanced.

FAQ:

Q1: What is a pool volume calculator, and how does it work?

A: A pool volume calculator estimates the number of gallons in your pool based on its shape, length, width, and depth. It’s essential for proper chemical dosing and water maintenance.

Q2: How do I calculate how many gallons my pool is manually?

  • A: Use these formulas: Rectangular: Length × Width × Average Depth × 7.5
  • Round: Diameter × Diameter × Average Depth × 5.9
  • Oval: Length × Width × Average Depth × 5.9

For irregular pools, divide the pool into simple shapes, calculate each section, and sum the totals.

Q3: What is the best online pool gallon calculator?

They provide instant gallon estimates and guidance on chemical dosing.

Q4: How do I use a pool size chart to estimate water volume?

A: Pool size charts list common pool dimensions with corresponding gallons. Use them for a quick reference instead of manual calculations. Charts exist for both in-ground and aboveground pools.

Q5: How can I find the volume of an abovegroundpool?

A: Most aboveground pools are round or oval. Measure the diameter (or length and width) and depth, then use the standard formulas or check an above-ground pool size chart for common sizes.

Q6: How do I calculate the volume of an irregular or freeform pool?

A: Divide the pool into simpler shapes like rectangles, circles, or ovals. Measure each section, calculate gallons individually, and then sum the totals. Don’t forget to account for tanning ledges or shallow benches.

Q7: Can HydroComm help me manage my pool water chemistry?

A: Yes! The HydroComm Smart Pool Monitor & Underwater Comm Device | Aiper is a smart water monitoring device that tracks pH, chlorine, and other key parameters in real time via an app, helping you maintain balanced water without constant manual testing.

Q8: Why is knowing my pool volume important for HydroComm?

A: Accurate pool volume ensures that any chemical dosing guidance from HydroComm is proportional to your pool’s actual water, avoiding over- or under-treatment

.Q9: How do I measure average depth for my pool?

A: Measure the shallow end and deep end, then divide by two. For irregular pools, take multiple readings across different sections to calculate an approximate average depth.

Q10: Can I use a pool gallon calculator for chemical planning?

A: Yes. Once you know the pool’s gallons, you can calculate the exact amount of chlorine, shock, or stabilizer needed. Tools like Pentair and TFP calculators often include chemical dosing recommendations.

Q11: How do I convert my pool size chart data into gallons?

A: Find your pool’s length, width, and depth on the chart. Then multiply as per the formulas (rectangular × 7.5, round × 5.9, oval × 5.9). This gives a reliable gallon estimate.

Q12: Are there apps or devices that combine pool volume and water monitoring?

A: While pool volume calculators handle gallons, smart devices like HydroComm track water chemistry. By combining both, you can ensure accurate chemical dosing and safe swimming water throughout the season.