Kind of a strange question...

Suppose you brew your coffee to your liking, a v60 filter or an espresso. The ingredients are water and coffee grounds. But how much 'coffee' is there actually in the end cup? That is, if you would be able to extract the water from the cup; what percentage of the original cup of coffee would be left?

Has anyone ever read anything about this?

What I'm trying to get at is; the strength of a cup of coffee. Everyone uses the saying a strong cup of coffee when they quite often refer to the roasting. This could also be a reference to how diluted coffee is; e.g. an americano. But what percentage of that americano would then be 'real coffee'.

  • 1
    I think you're talking about two related measurements: the absolute quantity of "coffee" pulled into water from beans when brewing is called extraction. How concentrated the final brew is (i.e., how many units of coffee per unit of water), this is called strength. See this question for a comparison of the two terms. See also questions like this and this for more on how to measure. Is that your question?
    – hoc_age
    Apr 19, 2017 at 3:00

1 Answer 1


This is discussed in many different contexts many times, I assume. So, I can say not a very strange question in essence.

I advise you to check a previous answer first. It includes a very nice chart and the ideal point for quality brewing of coffee. Also, it shows the extraction ratios, a hint of TDS (total dissolved solids) etc. I copy its link just below:

As you see, if you can manage to brew an ideal coffee, you can extract only around 20% of the valuable "essence" from the core of the beans. That's the reason why some of the members of Coffee SE tries to re-brew the used grounds for a second time (I assume), as you can follow below:

Then, of course, some other members discuss the TDS part to find the golden brewing point at the first chart. The easiest way to follow that point repeatedly is done by a refractometer. It is a device that can measure opaqueness. So, by measuring the opaqueness of your brew, you may reason on the amount of dissolved coffee "essence" in the water; therefore you may estimate the strength of your cup.

I hope these previous answers and the path I've directed you helps you.

  • 1
    TDS. It even has a term! This is exaclty what I'm looking for; as with alcoholic drinks, we talk about how strong a drink is referring to the percentage of alcohol in it. As the coffee culture grows, we might get in a more thorough vocabulary of coffee. Atm, everything is just called 'coffee'; the beans, grounds, liquid etc. And again, the 'strength' of coffee is also amibiguous a lot of the time. A filter has more caffeine, but everyone would find an espresso more 'strong'. Which comes down to TDS in this very case :). Very interesting.
    – onimoni
    Apr 11, 2017 at 5:56
  • @onimoni Yes, it has its own term. But be careful, TDS is a measure that is used with many other liquids. For example, the water with you brew has its own TDS preferable range, even with some alcoholic drinks it's used, not only the alcohol percentage matters. It's a chemical thing, it is strongly related with concentration. Apr 18, 2017 at 15:51

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