What is ideal dimension size for a home listening room?


Is it a cozy size, large living room, 10 x 15, 20 x 30, some where in between?  I guess it shouldn’t be square.  Let’s assume ceiling is 7 1/2.  Heard ceiling height means a lot.
emergingsoul
arion, thanks for the reply.  Your approach makes sense.  

I'm grateful for the online calculators we have, but we could certainly use some that are a bit more sophisticated.  It has been 48.5 years since I finished my last quarter of calculus, and I didn't use it enough professionally to maintain competence.  But I would think a physics graduate student could make quick work of generating a  calculator for non parallel walls at least for calculating axial modes.  The most difficult part might be figuring out how to present the output visually in a clear fashion.  

In some respects, I like the REW room calculator, because it allows you to introduce speaker and listening position into the model as well as room dimensions.  Unfortunately, my speakers have side firing woofers, so the model doesn't make the best predictions in my case. 
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Awfully great comments herein.

i believe great amp power would be essential especially in a smaller room to allow great control over lower volumes.

Curious on thoughts of an ideal size for a b&w 803 d3 or their very dominant 802 in a residence.  My belief is that anything below 15 x 20 would be on the edge of being comfortable for an 803. Great Danes are unable to thrive in a nyc apartment.