Great question! I tend to get this question often when out at Wolfforth Farmers Market.
The correct answer: the amount that makes the cup YOU drink taste the way YOU think tastes best to you. The unfortunate part of that answer is the overall vagueness.
There are many packages (including some of TPRs) that will state use 1-2 tablespoons per 6 oz of brewed water. WOW, that is a huge range. Measuring spoons labeled as “coffee spoons” are marked as 2 tablespoons. I have several and each measures a different amount by weight. Maybe only a partial gram difference, but they are different!
I have heard some say 2 heaping scoops. Whose heaping is heaping?
I have found as I have moved more into the specialty coffee that measuring by weight is a much more accurate and concise determination of the amount of coffee for any brew I am preparing, whether an espresso shot, individual pour over, French press or a drip brewer. This has allowed me to replicate the cup over and over. In addition, it allows experimentation in strengthening or weakening the brew based on taste.
So, you might ask: Well how much coffee do I use? Remember those math equations you never thought you might use? We are getting close! Lots of research in dissolved solids, extraction rate and overall cup taste have been performed over many years. This research has found that the ideal water to coffee ratio (W:C) to be 17:1.
Who is this ideal for? Me most of the time; however, sometimes I like my coffee to have a little bit bolder flavor and slightly more extracted caffeine, so I change to a 16:1 ratio and sometimes I like it to be a little more tea like, thus an 18:1 ratio.
I have found that weight is a much more accurate method of determining and correctly making my coffee regardless of brewing type. Does this mean you need to weigh the water for brewing? Sometimes! If you can very accurately measure the volume then no; however, if you are using the decanter that came with your coffee pot, you might want to invest in a graduated measurer.
Well, do you need special equipment for changing up your determination of coffee grounds? Possibly, but any kitchen scale will work, with a digital scale being more accurate than a manual or analog.
Why take this much effort for brewing a cup of coffee? Well you have, or are in the process of, investing in high quality, fresh roasted coffee. Don’t you want to have the highest possible success in brewing the best possible cup to enjoy?
Which ratio will be right for you? You will have to find out on your own. Try a couple of different brew strengths and let us know your thoughts on each. You might also find that when your coffee origin changes you might enjoy a different ratio!
Good luck and have a great cup of coffee!