Pool volume is the total amount of water your pool contains, and it affects everything from chemical balancing and heating efficiency to equipment sizing. Every pool owner should know the volume of their pool—and ePoolSupply can help you determine yours if you don’t know it.
Instead of wrestling with math, you can use our pool volume calculator to get accurate results in seconds. Just enter your pool’s measurements and depth and let us do the work.
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Why Pool Volume Matters
Knowing your pool volume is the first step in effective pool care. If you don’t know your pool’s volume, you’re basically guessing when it comes to treatment—and that can be a waste of time and money.
Here’s why knowing your pool’s volume matters:
- Accurate Chemical Dosing – Whether you’re adding chlorine, shock, or balancing pH, you need the right dosage for your pool size. Too little won’t sanitize; too much can cause irritation.
- Equipment Sizing – Pumps, filters, and heaters are all rated for specific water volumes. An undersized pump may struggle to keep up, while an oversized heater can waste energy.
- Energy & Cost Efficiency – Avoid overusing pool chemicals, running your pump longer than necessary, or overheating water.
- Water Testing Accuracy – Pool water testing is only as good as the measurements you use. It’s recommended to test your pool water weekly.
Different Pool Shapes and How They Affect Volume Calculations
Your pool’s shape determines how you’ll calculate its volume. A perfect rectangle is straightforward, but freeform or kidney-shaped pools require a bit more work.
Common pool shapes include:
- Rectangular or square
- Round
- Oval
- Kidney-shaped
- Irregular or freeform
Rectangles and circles need only length/width or diameter; kidney shapes may need you to divide the pool into sections. Pools with both shallow and deep ends require an average depth calculation.
How to Measure Your Pool
Before using the pool volume calculator or formulas, you’ll need a few accurate measurements. Always measure in feet for the easiest conversion to gallons.
Rectangular and Oval Pools
- Measure the length (longest side).
- Measure the width (shortest side).
- Measure the depth: take shallow depth, deep depth, and calculate the average.
Example:
Shallow end: 3 ft, deep end: 6 ft
Average depth = (3 + 6) ÷ 2 = 4.5 ft
Round Pools
- Measure the diameter across the widest point.
- Measure the average depth as above.
Example:
Diameter: 24 ft, Average depth: 4 ft
Sloped Pools
For pools with a slope from shallow to deep:
- Measure the shallow end depth.
- Measure the deep end depth.
- Average the two numbers.
Check out the ANSI standards for residential pools.
Pool Volume Formulas by Shape
The exact formula you use will depend on your pool’s shape. Once you have your measurements, plug them into the correct equation below. We’ve also included references so you can estimate without doing the math.
Rectangular or Square Pools
The formula for finding the volume of a rectangular or square pool is:
Length × Width × Average Depth × 7.5 = Volume (in gallons)
Example:
Length: 30 ft × Width: 15 ft × Average Depth: 4.5 ft × 7.5 = 15,187.5 gallons
Rectangular Pool Volume Chart
Here's a "cheat sheet" for quick reference with common rectangular pool sizes and volume.
| Length (ft) | Width (ft) | Avg. Depth (ft) | Volume (gallons) |
| 24 | 12 | 4 | 8,640 |
| 30 | 15 | 4.5 | 15,188 |
| 40 | 20 | 5 | 30,000 |
| 50 | 25 | 6 | 56,250 |
Round Pools
The formula for finding the volume of a round pool is:
Diameter × Diameter × Average Depth × 5.9 = Volume (in gallons)
Example:
Diameter: 24 ft × 24 ft × 4 ft × 5.9 = 13,612.8 gallons
Round Pool Volume Chart
Here's a "cheat sheet" for quick reference to find the volume of common sizes of round pools.
| Diameter (ft) | Avg. Depth (ft) | Volume (gallons) |
| 12 | 4 | 2,722 |
| 18 | 4.5 | 6,878 |
| 24 | 4 | 13,613 |
| 30 | 5 | 22,125 |
Oval Pools
The formula for finding the volume of an oval pool is:
Length × Width × Average Depth × 5.9 = Volume (in gallons)
Example:
Length: 30 ft × Width: 15 ft × Avg. Depth: 4 ft × 5.9 = 10,620 gallons
Oval Pool Volume Chart
Here's a "cheat sheet" for quick reference to find the volume of common sizes for oval pools.
| Length (ft) | Width (ft) | Avg. Depth (ft) | Volume (gallons) |
| 16 | 10 | 4 | 3,776 |
| 24 | 12 | 4.5 | 7,632 |
| 30 | 15 | 4 | 10,620 |
| 33 | 18 | 5 | 17,541 |
Irregular or Kidney-Shaped Pools
Kidney-shaped pools are best calculated in two sections:
- Divide the pool visually into two rectangles or circles.
- Calculate each section’s volume separately.
- Add the totals together.
Example:
Section A: 15 × 10 × 4 × 7.5 = 4,500 gallons
Section B: 20 × 12 × 5 × 7.5 = 9,000 gallons
Total: 13,500 gallons
Tip: For very freeform designs, use our calculator for the most accurate result.
Using the Pool Volume Calculator Tool
To make things even easier, we’ve added an interactive pool volume calculator for your convenience.
Instead of crunching numbers manually, you can select your pool shape, enter your measurements, and instantly see your pool’s volume in gallons. This saves time and eliminates guesswork.
Tips for Accuracy
To get the most reliable results from your pool gallon calculator, follow these tips:
- Double-check measurements — especially depth, which affects calculations the most.
- Measure in feet — it’s easier for gallon conversions.
- For irregular pools — take multiple measurements and average them.
- Recalculate after renovations — changing your liner, adding steps, or reshaping your pool can change capacity.
- Account for seasonal changes — water levels may shift with pool water evaporation, rain, or splash-out.
If you need ongoing help with upkeep, explore ePoolSupply’s pool maintenance guide for step-by-step seasonal tips.
Final Tip: Once you know your pool’s volume, keep it handy! Bookmark this page so you can quickly reference your measurements before adding chemicals, opening for the season, or making equipment upgrades.
FAQs: Pool Volume Basics
Can I use the same formula for above-ground and in-ground pools?
Yes. The formulas are the same for above-ground pools and in-ground pools. The only difference is the shape and depth measurements.
How do I measure average depth in my pool?
Measure average pool depth by adding the shallow end and deep end depths together, then dividing by two.
What’s the easiest way to calculate round pool volume?
You can use our round pool volume calculator. Simply enter the diameter and average depth.
Why is knowing my pool’s volume important?
Understanding your pool’s volume is important for selecting the right amount of chemicals and equipment, which helps maintain water quality.
How often should I recalculate pool volume?
You should only recalculate if you change the pool’s size, shape, or depth.