Calculating volume of an oval pool? I'm deeply confused now

[amphigory]

Okay, so I have an 18x34x4 foot oval pool.

PoolCalculator.com tells me that this pool holds 16,200 gallons of water.

The back of the pool chemical bottles and most online calculators tell me it holds 14,387 gallons of water.

Now... maybe I'm doing this all wrong, but my OWN calculations tell me that PoolCalculator.com is right, and that most of the websites out there are dead wrong. Anybody care to comment on WHY the "standard" formula is off by close to 2000 gallons? If anything, I would expect the chemical companies to exaggerate the volume of pools (thereby selling more chemical)

Thanks,

Patrick

 

[JasonLion]

There are two definitions of an oval, the mathematical definition, and the pool definition. A mathematical oval is like a circle that has been stretched, while a pool oval is a rectangle with half round end caps. If you use the mathematical definition of an oval you get the volume that those other calculators are giving you.