An approximate mathematical formula used to compare and contrast the size of a woman's breasts to the size of her ass. Typically if one is bigger than the other, the woman in question has a skewed or poor tits- to- ass ratio - If the two are relatively proportional, then she has an ideal tits- to- ass ratio. In some cases, the formula can be trivialized when the woman's good looks outweighs both of those factors.
"Sarah's got them titties tho"
"Yeah but her tits-to-ass ratio is all off, man"