The other week, I had just received a bag of very nice Panamanian
beans, roasted to about a City+. My precision scale is currently dead,
so I used a crude kitchen scale to work out volume to grams equivalent
measurements. Basically, I weighted a volume of two cups, which my
regular kitchen scale could give a moderately accurate weight on.
Since their are 32 tablespoons in two cups, I could simply divide and
get the tablespoon equivalent.
In this case, a 2 tablespoon measure held 10.5 grams ( I've rounded a
bit, this is good enough for engineering purposes). This is perfect, as
10.5 grams is what I typically use for 6 oz of drip coffee. So in this
case, 1 lb of coffee can give me 87 tablespoons of unground coffee and
43 6oz servings.
I repeated the process with a bag of rather large Yirg beans roasted to
full city, and got a different relationship. Darker roasts tend to be
lighter in weight and the bigger beans means it doesn't pack together
as tightly. 2 TBS measure held about 9 grams.
I'll let you do the math. I get the same number of servings (since I
use weight and not volume) but a different number of tablespoons.
I didn't remeasure after grinding, as that's pretty pointless. The burr
grinding process makes very fluffy grounds, so how you scoop them can
make a big difference in volume, depending how packed they get in the
process. You'd basically have to sift them like flour before making the
volume measurement. That's why I measure, by weight, the amount of
beans I need, then grind them and dump them into whatever device I'm
using to make coffee. (Espresso is an exception, I generally just grind
until I've filled the portafilter).
Maybe ground commercial canned coffee has packed down by sitting in
the can so long that you can get a consistent measure, I wouldn't know.