1. What is Apparent Attenuation?

Apparent Attenuation (AA) is a measure of how much sugar has been converted to alcohol and carbon dioxide during fermentation in brewing. It's expressed as a percentage of the original extract that has been fermented.

2. How Does the Calculator Work?

The calculator uses the apparent attenuation formula:

Where:

• \( OG \) — Original gravity (dimensionless)
• \( FG \) — Final gravity (dimensionless)

Explanation: The formula compares the difference between original and final gravity to determine what percentage of sugars were fermented.

3. Importance of Attenuation in Brewing

Details: Attenuation helps brewers understand fermentation efficiency, yeast performance, and expected alcohol content. Different yeast strains have characteristic attenuation ranges.

4. Using the Calculator

Tips: Enter original gravity (OG) and final gravity (FG) as measured by hydrometer or refractometer. Both values must be greater than 1 and OG must be higher than FG.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical attenuation range?
A: Most ale yeasts attenuate 65-75%, while lager yeasts typically reach 70-80%. Some highly attenuative strains can exceed 80%.

Q2: How does this differ from real attenuation?
A: Apparent attenuation doesn't account for alcohol's effect on specific gravity. Real attenuation is more accurate but harder to calculate without lab equipment.

Q3: Why is my attenuation lower than expected?
A: Could be due to incomplete fermentation, poor yeast health, low fermentation temperature, or unfermentable sugars in the wort.

Q4: Can attenuation be too high?
A: Yes, over-attenuation can lead to thin, dry beers. Some styles (like brut IPA) intentionally achieve very high attenuation.

Q5: How does mash temperature affect attenuation?
A: Higher mash temps (156-160°F) create more unfermentable sugars, lowering attenuation. Lower temps (148-152°F) produce more fermentable sugars, increasing attenuation.