# Thread: Pool Math Oval Shaped Pool Volume Calculation

1. ## Pool Math Oval Shaped Pool Volume Calculation

Just happened to be figuring for an oval shaped pool and noticed my math and pool math doesnt come out the same.

To figure area for an oval shape I use this formula. Say for 1000 by 500 feet oval shape with 10 foot depth.

width radius (250) x length radius (500) x 3.14159265 (pi) = 392699.08125 square feet.
square feet x depth = 3926990.8125 cubic feet.
cubic feet x 7.48 gallons in a cubic foot = 29,373,891.2775 gallons of water in the oval shape.

Pool math shows 33,389,300 gallons of water.

When I calculate for a circle with the same formula with 500 by 500 feet with 10 foot depth I get 14,686,945.6 gallons of water while pool math gets 14,688,000 which would be right or close enough but the oval shape is way off.

Whats wrong here?

2. ## Re: Pool Math Oval Shaped Pool Volume Calculation

In the last scenario, I don't know what the minor difference is, but you are talking about 1000 gallons in almost 15 Million gallons of water which, is nearly nothing in that volume.

3. ## Re: Pool Math Oval Shaped Pool Volume Calculation

looks like a rounding error to me. I want to see a pic of your 15m gallon pool!!!

4. ## Re: Pool Math Oval Shaped Pool Volume Calculation

In swimming pool universe, an "oval" is a rectangle with two half round end caps. No one ever builds a true geometric oval swimming pool.

This totally confused me for a week when I was writing the code. My first draft results never matched any of the other calculators.

5. ## Re: Pool Math Oval Shaped Pool Volume Calculation

smackdab, I am only asking from pure curiosity, but why are you using such giant numbers in the scenarios?

6. ## Re: Pool Math Oval Shaped Pool Volume Calculation

That is the size of my nature pool. It is so clear that sometimes I drive my lawnmower off in it because I cant tell the water is even there. Here is a pic of me in my boat in it. See it looks like I'm flying.

No I just used the big numbers to super impose what what going on. As numbers get bigger so does the margin of error. As I stated above the second scenario or "round" was right or close enough.

I see now why the calculation is what it is. A pool oval is a rectangle with two half circles and not an ellipse.

7. ## Re: Pool Math Oval Shaped Pool Volume Calculation

Ok, I figured as much but didn't want to presume too much. Thanks.

8. ## Re: Pool Math Oval Shaped Pool Volume Calculation

Originally Posted by smackdab
That is the size of my nature pool. It is so clear that sometimes I drive my lawnmower off in it because I cant tell the water is even there. Here is a pic of me in my boat in it. See it looks like I'm flying.

I want to be there right NOW!!!

9. ## Re: Pool Math Oval Shaped Pool Volume Calculation

Originally Posted by JasonLion
In swimming pool universe, an "oval" is a rectangle with two half round end caps. No one ever builds a true geometric oval swimming pool.

This totally confused me for a week when I was writing the code. My first draft results never matched any of the other calculators.
I broke down an oval shaped pool into a rectangle and two halves of an ellipse.

With a 35' wide 100' long 12' deep oval pool I came up with 297,305 gallons while pool math shows 290,600 gallons. About a 2% difference, no big deal. There is a variable where the staight edge of the pool side starts to curve to form the oval shape that can make a difference in the volume of the pool but all things considered I would say you done good.

10. ## Re: Pool Math Oval Shaped Pool Volume Calculation

smackdab, it seems to me you have calculated something incorrectly. A 35'x100' oval 12' deep is a 35' circle (86,382 gallons) (the two half circle end caps) plus a 35'x65' rectangle (204,231 gallons) (the remaining rectangle), which totals to 290,613 gallons.

11. ## Re: Pool Math Oval Shaped Pool Volume Calculation

I didnt calculate 2 halves of a round circle with that being a rectangle and one full circle. I calculated an ellipse because I didnt know if oval pools had a perfect half circle on both ends or its more of a flat circle (that being an ellipse). I just guessed and calculated 100' total length, 75' straight edge, 35' width, and 12' deep. That would make my circle 35' x 25'. So you can see the difference in volume from where the pool starts to form an oval shape.

When I calculate a perfectly round circle I get 290,563 gallons so we are neck and neck. This would be 100' total length, 65' straight edge, 35' width, and 12' deep and would make my circle 35' x 35'.

Just curious what are you using for pi and how many gallons are in a cubic foot in your calculation? I used 3.14159265 and 7.48. Use these and see if you come up with what I got.

12. ## Re: Pool Math Oval Shaped Pool Volume Calculation

A half circle end cap is by definition part of a circle, not an eclipse.

Rounded to the nearest 100 gallons it is 290,600 gallons, regardless of which approximation of pi and gallons per cubic foot you use, which is what PoolMath said in the first place.

13. ## Re: Pool Math Oval Shaped Pool Volume Calculation

Yes a half circle would be half of a circle and would be perfectly round. If oval pools have 2 half circles on the end then your calculation is correct and so was mine in the middle of post #11. Most pools likely do have half circles but I have no idea whether they do or dont thats why I figured in an ellipse and not a circle.

I wasnt trying to start an argument over your calculations but merely trying to understand.

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