[9westgirlfla]

Bra sizing calculators are soo messed up.

Two years ago I was 39 under breast and 41 across my nipples ..

According to calculators, that's a 40b cup. 

My poor chest swims in a 40b ..but a 38b is ok.

Now I measure my chest, still 39 band but 43 across my nipples.

Now the calculator thinks I am a 40d.

ROTFLMAO .. 

In reality I am still  a 38b, I just fill the cups out better.

My wife is a full 40d, no way in hell could I fill those cups.

I too have had that experience and initially it made buying a bra online frustrating. Add to that the crazy variances between brands and materials used makes for a hit and miss proposition. 

I currently have a 4" difference between my chest (36/40) and as you know most of the charts put me into a D where in reality a "B" fills completely with maybe just a hint of overflow in some brands and my GF's C bras swim on me. As long as I know the material content of the bra (non stretchy vs. spandex content) I can buy a 36B (or sister size 38A but rare as hen's teeth) and be highly confident it will fit. 

So, if "I" were to make a chart it would look like this:

 1 inch or less AA
 2 to 3 inches A
 4 inches B
 5 inches C  

The following calculator comes close (depending on minor variations) and whether you select male or female at birth:

https://www.abrathatfits.org/calculator.php