In my area, whole coffee beans don't have the selection that pre-ground offers. I have experimented with using pre-ground beans, and found that while it isn’t ideal, it does work. There are two things to watch out for if using pre-ground coffee. The first is that since it isn't coarsely ground, you will need a mesh sieve or coffee filter to strain it (not cheesecloth). My own French press maker strains pre-ground coffee without leaving any grounds left behind. Also, because you are using a finer ground, less beans are needed. I usually use 3/4 cup whole beans or about 1/2 cup of pre-ground plus 1 Tbsp.