Before answering this question, you should know that coffee beans come in different criteria that can affect their density and overall weight. As a result, not all coffee beans are created equal.
According to a lot of variables, coffee beans can have different ratios of internal ingredients. Also, it can have different levels of moisture and more. Also, people enjoy different kinds of coffee ranging from mild to strong and bitter ones.
So, the exact number of coffee beans in a single cup depends on a lot of aspects. For the sake of argument, let’s consider the most average cup of coffee. Ideally, a cup of coffee has about two tablespoons of coffee grounds per 6 ounces cup. This makes it easy to measure if you need to measure coffee without a scale. This translates to about 7 to 10 grams of coffee grounds per cup. The ‘golden ratio’ is considered to be somewhere between 1:15 to 1:18 parts of coffee to water. In other words, you need between 15 and 18 times the amount of water compared to the amount of ground coffee to end up within the golden coffee to water ratio for brewing coffee at home.
As a rule of thumb, 10 grams of coffee grounds come from about 76 coffee beans in total. In other words, every coffee bean produces an average of ⅛ grams of final ground coffee that ends up in your cup.