Apparent Attenuation Calculator

Summary

Enter original gravity and final gravity to instantly calculate your beer's apparent attenuation percentage.

How it works

1. Measure your wort's original gravity (OG) before fermentation begins.
2. After fermentation is complete, measure the final gravity (FG) with a hydrometer or refractometer.
3. Enter both gravity readings into the calculator.
4. The tool computes the apparent attenuation percentage using the formula: AA% = ((OG - FG) / (OG - 1)) × 100.
5. Compare your result with your yeast strain's stated attenuation range to assess fermentation health.

Use cases

• Verify that fermentation is complete before packaging your homebrew.
• Evaluate yeast health and pitch-rate effectiveness batch to batch.
• Compare actual attenuation against the yeast manufacturer's stated range.
• Diagnose stuck fermentations when attenuation is abnormally low.
• Fine-tune mash temperature to hit target attenuation and residual sweetness.
• Calculate attenuation for recipe formulation in all-grain and extract brewing.
• Track fermentation progress over multiple gravity readings.
• Identify yeast strains that perform best in your brewing conditions.

Frequently Asked Questions