Attenuation (brewing)

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Amount of sugar converted to alcohol

title: "Attenuation (brewing)" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["brewing"] description: "Amount of sugar converted to alcohol" topic_path: "general/brewing" source: "https://en.wikipedia.org/wiki/Attenuation_(brewing)" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Amount of sugar converted to alcohol ::

In brewing, attenuation refers to the conversion of sugars into alcohol and carbon dioxide by the fermentation process; the greater the attenuation, the more sugar has been converted into alcohol. A more attenuated beer is drier and more alcoholic than a less attenuated beer made from the same wort.

Attenuation can be quantified by comparing the specific gravity — the density of a solution, relative to pure water — of the extract before and after fermentation, quantities termed the original and final gravities. Specific gravity can be measured by buoyancy, with a hydrometer. The higher the specific gravity of a solution, the higher the hydrometer floats.

Apparent attenuation is calculated using the equation: AA=\frac{OG-FG}{OG-1} where AA is apparent attenuation and OG and FG are the original and final gravities. For example, if a beer's OG is 1.05 and its FG is 1.01, then the apparent attenuation is: \frac{1.05-1.01}{1.05-1}=0.80

Attenuation can range between 0.33 and 0.80, but is usually 0.75.

Because fermentation produces ethanol, which has a lower density than water (gravity of 0.787 at °C ), the apparent attenuation overestimates the actual percentage of sugars consumed. Brewers generally refer to this apparent attenuation when using the word without qualification, although the measurement of real attenuation — the actual percentage of sugar consumed by the yeast — is an important indicator of yeast health and for producing certain styles of beer. A beer which does not attenuate to the expected level in fermentation will have more residual sugar and thus be sweeter and heavier-bodied.

References

References

  1. "Everything You Need to Know about Attenuation".
  2. Andrew Campbell, ''The Book of Beer'', 1956, p.53
  3. "Specific Gravity - Liquids".
  4. Palmer, John. "6.1 Yeast Terminology".
  5. "Apparent and Real Attenuation for Beer Brewers – Part 2".
  6. Palmer, John. (July–August 2009). "Attenuation: Advanced Brewing". Brew Your Own.

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