As I noted in a previous post, I’m currently learning to like coffee. As a part of this process, I’ve bought an AeroPress coffee maker and a Kyocera grinder. Thus, I can grind my own coffee beans just before brewing myself a fresh cup.
So what’s the relationship between the volume of beans in the grinder and the volume of grounds that they produce? The instructions that came with my AeroPress suggest using two scoops (measured with their included scoop) of grounds per 10 oz. cup of coffee.
Since I’d like to grind my beans fresh everyday, and I don’t want to waste any coffee, I’d like to know how many beans to use. Thus, I decided to do an experiment…
I start by measuring out a scoop of beans and putting them in my burr grinder. I then ground them up at an intermediate coarseness and scooped them out of the glass container.
Surprisingly, the grounds took up a bit more volume than the beans themselves. I figured that there was a lot of wasted space between the unground beans, so grinding would reduce the volume.
Quite the opposite, grinding the beans actually increased their overall volume — essentially “fluffing” them up a bit. I repeated this process one more time to be sure, and I got the same result.
My best guess is that there was a ca. 20% increase in volume, so if you want X volume of grounds then you should start out with 0.85X volume of beans.
Of course, your mileage may vary depending on the beans, grinder, desired coarseness, etc.