Owning a swimming pool is exciting, but it comes with responsibilities such as cleaning, maintaining, and treating the water. One of the most essential tasks pool owners face is knowing how many gallons of water their pool holds. This number impacts everything—from how much chlorine you should use to how long it takes to fill your pool.

That’s where the Above Ground Pool Gallon Calculator comes in handy. Instead of doing math by hand, this tool allows you to input your pool’s dimensions and get instant results. Whether you own a round, oval, or rectangular pool, this calculator will provide a quick and accurate estimate of your pool’s water capacity in gallons.

How to Use the Above Ground Pool Gallon Calculator

Using the tool is very straightforward. Here’s a step-by-step guide:

Select Your Pool Shape
- Choose from Round, Oval, or Rectangular in the dropdown menu.
Enter the Dimensions
- For round pools, enter the diameter and average depth.
- For oval pools, enter the length, width, and average depth.
- For rectangular pools, enter the length, width, and average depth.
Click “Calculate”
- The calculator instantly shows the total gallons of water your pool holds.
Use “Reset” if Needed
- The reset button clears inputs and reloads the page for fresh calculations.

Practical Example

Let’s say you own a round above ground pool with a 24 ft diameter and an average depth of 4 ft.

Choose Round from the shape menu.
Enter 24 for diameter and 4 for depth.
Click Calculate.

The calculator will display:

Pool Water Capacity: ~13,565 gallons

This is the amount of water you’ll need to fill your pool, and it’s the number you’ll use when balancing chemicals like chlorine or shock.

Why Knowing Pool Gallons Matters

Chemical Balance: Adding too much or too little chlorine, algaecide, or pH adjuster can be unsafe. Proper gallons ensure correct dosing.
Filling Time: Helps estimate how long it will take to fill your pool with a garden hose.
Water Treatment Costs: Lets you budget more accurately for monthly maintenance.
Heater Sizing: Pool heaters and pumps require accurate gallon capacity to work efficiently.
Drain & Refill Planning: Knowing gallons helps calculate how much water is replaced and how much chemical rebalancing is needed.

Features & Benefits of the Tool

✅ Supports Multiple Shapes – Round, oval, and rectangular pools.
✅ Accurate Results – Uses proper volume formulas with conversion to gallons.
✅ Instant Output – Results appear in seconds.
✅ User-Friendly – Simple input fields, no complicated setup.
✅ Free to Use – No sign-up or fees required.
✅ Reset Option – Quickly start over with new dimensions.

Tips for Accurate Pool Measurements

Measure across the widest points of your pool.
Always use average depth if the pool slopes. Add shallow and deep ends, then divide by two.
Double-check units. Make sure dimensions are in feet, not inches or meters.
If you have an irregular pool shape, break it into sections (rectangular + semicircular ends) and calculate separately.

FAQs About the Above Ground Pool Gallon Calculator

1. Why do I need to know the gallons in my pool?

Because all water treatments, like chlorine and shock, depend on pool volume for safe dosing.

2. Does the calculator work for inground pools?

Yes, as long as the shape is round, oval, or rectangular, you can use it for inground pools too.

3. What if my pool is kidney-shaped?

You can approximate by dividing it into sections (two ovals or a rectangle + circle) and adding the results.

4. Is the depth measurement average or exact?

Use the average depth if the pool has both shallow and deep ends.

5. Can I use the calculator for hot tubs?

Yes, but only if your hot tub is roughly round, oval, or rectangular.

6. How accurate is this calculator?

It gives a close estimate. Actual volume may vary slightly due to pool walls, slopes, or irregular features.

7. What does the “7.48” number mean in the formula?

One cubic foot of water holds 7.48 gallons, so it converts cubic feet to gallons.

8. How do I calculate gallons for a sloped pool?

Take the shallow depth + deep depth ÷ 2 to get the average depth, then enter it.

9. Do above ground pools usually hold less water than inground ones?

Yes, above ground pools tend to be shallower and smaller, so they usually hold fewer gallons.

10. Can I use this tool if my pool has steps?

Yes, but steps add only a small volume of water, so you can safely ignore them.

11. How many gallons are in a 12 ft round pool with 3 ft depth?

About 2,540 gallons.

12. How long does it take to fill a pool with a garden hose?

On average, a garden hose delivers 8–10 gallons per minute. Divide your pool’s total gallons by that flow rate.

13. Will this tool help me size a pool heater?

Yes, most heater manufacturers recommend models based on pool gallon capacity.

14. Can I use inches instead of feet?

No, the tool requires feet. Convert inches to feet first (e.g., 24 inches = 2 feet).

15. How many gallons does a 15×30 oval pool with 4 ft depth hold?

Roughly 10,600 gallons.

16. Does water level affect gallons?

Yes. If your pool isn’t filled to the top, adjust the depth measurement accordingly.

17. Can this calculator work for metric measurements?

Not directly. Convert meters to feet before entering values.

18. Why is my pool chemical balance always off?

It may be because you’re estimating gallons incorrectly. Using this calculator can help fix that.

19. How many gallons are in a rectangular 16×32 pool with 4 ft depth?

About 15,325 gallons.

20. Is this tool free forever?

Yes, the calculator is completely free to use anytime.

Final Thoughts

The Above Ground Pool Gallon Calculator is a must-have tool for any pool owner who wants to keep their water safe, balanced, and cost-effective. By quickly calculating your pool’s water capacity, you’ll save time, money, and effort in maintaining a crystal-clear swimming environment.

Whether you’re filling your pool for the first time, adding chemicals, or planning a new pool purchase, this tool provides the accuracy you need at the click of a button.