<p>Though I don't generally like to cite Wikipedia as my primary reference, it <em>does</em> in this case have a pretty good overview of <a href="http://en.wikipedia.org/wiki/Coffee_extraction" rel="noreferrer">terms related to coffee extraction</a>, re-summarized here:</p>

<p><strong><em>Extraction:</em></strong>
<br><strong>The <em>amount of the original mass</em> of the grounds that ends up in the brewed coffee</strong>. Though it certainly depends on the preparation method ("method of extraction", e.g., drip, moka, espresso, cold-brew, ...), the recommended extraction amount is <strong>about 20%</strong> (i.e., about 20% of the mass of the beans/grounds ends up in the brewed coffee). </p>

<p><strong>Less than ~15%-18% extraction is considered "under-extracted" and can be sour.</strong> That is, under-extraction is not just a matter of inefficiency: the result can be sour and unbalanced due to the fact that acids are extracted quickly. On the other hand, <strong>more than ~22%-25% extraction is considered "over-extracted" and can be bitter</strong>, because the bitter compounds are extracted later in the brewing process.  </p>

<p>These figures were generated by groups with lofty-sounding names like the <a href="http://en.wikipedia.org/wiki/Specialty_Coffee_Association_of_America" rel="noreferrer">Specialty Coffee Association of America</a>, the <a href="http://www.scaa.org/chronicle/2013/10/04/the-coffee-brewing-institute/" rel="noreferrer">Coffee Brewing Institute</a>, and the <a href="http://www.espressoitaliano.org" rel="noreferrer">Italian Espresso National Institute</a>. Also known as "solubles yield." See also <a href="http://www.coffeecuppers.com/Espresso.htm" rel="noreferrer">this article</a> on espresso extraction.</p>

<p><strong><em>Strength:</em></strong>
<br><strong>The <em>concentration</em> of the extracted compounds in the water.</strong> Basically, how much coffee is in the water per unit (volume or mass).</p>

<p>As noted in the question, there are also colloquial or vernacular uses of these terms (e.g., "strength" as relative flavour profile; "extraction" as the process of brewing, etc.) but the above seem to be the accepted tangible definitions of the terms.</p>

CC BY-SA 3.0
2015-02-24T20:05:41.217Z
As I was looking back on questions related to extraction, I thought we could use an explanatory Q/A on extraction. If anyone has anything to add, please comment or suggest edit! Or if you have a wholly different and better explanation, we could replace this answer...
hoc_age
CC BY-SA 3.0
2015-02-24T23:44:56.620Z
This seems like a way to earn rep...
Anthony Pham
CC BY-SA 3.0
2015-02-25T04:49:29.767Z
@hoc_age Your answer is certainly worthwhile - I'd rather see other answers posted in addition, not replacing!
Cascabel
CC BY-SA 3.0
2015-03-02T15:34:31.437Z
@PythonMaster What do you mean? Is that not how the site works?
speedfranklin
CC BY-SA 3.0
2015-02-24T20:05:17.107Z
2015-03-02T15:49:57.693Z
2015-03-02T15:49:57.693Z
hoc_age
<p>A number of questions use the terms <em>extraction</em> and <em>strength</em> in a broad sense like "how much stuff comes out of the coffee beans."</p>

<p>But "technically" speaking: <strong>What do the terms <em>extraction</em> and <em>strength</em> really mean for coffee?</strong></p>

<p>Some selected questions that discuss (but don't define as such) strength and extraction:</p>

<ul>
<li><a href="https://coffee.stackexchange.com/questions/44/what-does-the-strength-mean-in-numbers">Coffee package strength markings</a> are often just relative to others within a brand;</li>
<li><a href="https://coffee.stackexchange.com/questions/54/when-to-use-stirring-to-increase-extraction">Effect of stirring on extraction</a>;</li>
<li><a href="https://coffee.stackexchange.com/questions/128/what-preparation-method-yields-the-most-caffeine">Extracting caffeine and other compounds</a>;</li>
<li><a href="https://coffee.stackexchange.com/questions/96/how-will-cold-brewed-coffee-differ-from-traditional-hot-water-extraction-metho">Hot versus cold extraction</a>;</li>
<li><a href="https://coffee.stackexchange.com/q/26/262">This one</a> and <a href="https://coffee.stackexchange.com/q/408/262">this one</a> about espresso extraction.</li>
</ul>

<strength><terminology><extraction>
What do the terms extraction and strength mean?
hoc_age
# What do the terms extraction and strength mean?

(Asked by: username_0 on 2015-02-24)

A number of questions use the terms *extraction* and *strength* in a broad sense like "how much stuff comes out of the coffee beans."

But "technically" speaking: **What do the terms *extraction* and *strength* really mean for coffee?**

Some selected questions that discuss (but don't define as such) strength and extraction:

* [Coffee package strength markings](https://coffee.stackexchange.com/questions/44/what-does-the-strength-mean-in-numbers) are often just relative to others within a brand;
* [Effect of stirring on extraction](https://coffee.stackexchange.com/questions/54/when-to-use-stirring-to-increase-extraction);
* [Extracting caffeine and other compounds](https://coffee.stackexchange.com/questions/128/what-preparation-method-yields-the-most-caffeine);
* [Hot versus cold extraction](https://coffee.stackexchange.com/questions/96/how-will-cold-brewed-coffee-differ-from-traditional-hot-water-extraction-metho);
* [This one](https://coffee.stackexchange.com/q/26/262) and [this one](https://coffee.stackexchange.com/q/408/262) about espresso extraction.

**Tags:** strength, terminology, extraction


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## 1 answers

### Answer by username_0 on 2015-02-24. Score: 10 | Accepted answer

Though I don't generally like to cite Wikipedia as my primary reference, it *does* in this case have a pretty good overview of [terms related to coffee extraction](http://en.wikipedia.org/wiki/Coffee_extraction), re-summarized here:

***Extraction:***
  
**The *amount of the original mass* of the grounds that ends up in the brewed coffee**. Though it certainly depends on the preparation method ("method of extraction", e.g., drip, moka, espresso, cold-brew, ...), the recommended extraction amount is **about 20%** (i.e., about 20% of the mass of the beans/grounds ends up in the brewed coffee).

**Less than ~15%-18% extraction is considered "under-extracted" and can be sour.** That is, under-extraction is not just a matter of inefficiency: the result can be sour and unbalanced due to the fact that acids are extracted quickly. On the other hand, **more than ~22%-25% extraction is considered "over-extracted" and can be bitter**, because the bitter compounds are extracted later in the brewing process.

These figures were generated by groups with lofty-sounding names like the [Specialty Coffee Association of America](http://en.wikipedia.org/wiki/Specialty_Coffee_Association_of_America), the [Coffee Brewing Institute](http://www.scaa.org/chronicle/2013/10/04/the-coffee-brewing-institute/), and the [Italian Espresso National Institute](http://www.espressoitaliano.org). Also known as "solubles yield." See also [this article](http://www.coffeecuppers.com/Espresso.htm) on espresso extraction.

***Strength:***
  
**The *concentration* of the extracted compounds in the water.** Basically, how much coffee is in the water per unit (volume or mass).

As noted in the question, there are also colloquial or vernacular uses of these terms (e.g., "strength" as relative flavour profile; "extraction" as the process of brewing, etc.) but the above seem to be the accepted tangible definitions of the terms.

> **Comments:**
> **username_0**: As I was looking back on questions related to extraction, I thought we could use an explanatory Q/A on extraction. If anyone has anything to add, please comment or suggest edit! Or if you have a wholly different and better explanation, we could replace this answer...  
> **username_1**: This seems like a way to earn rep...  
> **username_2**: @username_0 Your answer is certainly worthwhile - I'd rather see other answers posted in addition, not replacing!  
> **username_3**: @PythonMaster What do you mean? Is that not how the site works?  

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