Not to be the math dork - again - but I think you mean 0.7 cm difference.
And if you're smaller than the derived width in one cross-section you should be wider in another.
Yes I acknowledged that people rarely have a symmetrical dick but the formula should give you a good ballpark...ie someone with a 5.5 inch girth probably won't have a 3 inch width unless their dick is flat as a pancake.
Surely I meant 0.7 cm... thanks for correcting me ;-) And it's pretty obvious that a pancake cock will have a girth in the 15-18 inches range