The standard guideline for most medium roast coffee bean bags is 2 tablespoons per 6 fl. oz. (1 cup in your liquid measuring cup). The Specialty Coffee Association of America has some interesting info on this, per this link. read more
There are two coffee beans within every coffee berry, and approximately 40 grams of coffee berries are needed for the 8 ounces of ground coffee used to make a single cup. The beans are hulled and roasted before use, reducing moisture and further decreasing the coffee's weight. read more
When you measure coffee beans by weight, coffee grounds weigh the same amount as beans-- 21 grams of beans results in 21 grams of ground coffee even though its volume will change. However, since tablespoon measurements of beans vary, 1 tablespoon of beans does not yield 1 tablespoon of grounds. read more