The deal density for a particular zip code may be calculated in a number of different manners. In some example implementations, a deal density in a particular zip code may be calculated and expressed as:

$\mathrm{Density}?\left(\mathrm{zip}\right)=\sum _{\mathrm{deals}}?f?\left(\mathrm{distance}??\mathrm{from}??\mathrm{deal}??\mathrm{to}??\mathrm{zip}\right)$

In such an example implementation, the function ? may be a decreasing function, such as 1/x, and the set deals may contain all active deals in a particular subcategory, for example. Since f is decreasing, a deal contributes more to the density of a particular location the close it is to that particular location. In an implementation that may be less computationally intense, ?(x)=1 in situations where the deal is within a particular zip code and ?(x)=0 otherwise, such that density in a zip code is equal to the number of deals in that zip code.