Fermentation Calculator

Original Gravity (OG) is the specific gravity of your wort or must before fermentation begins, indicating the sugar content. Final Gravity (FG) is measured after fermentation is complete, showing how much sugar has been converted to alcohol.

The standard formula (OG - FG) × 131.25 is most commonly used and accurate for most homebrewing situations. The alternative formula is more complex and accounts for additional factors but is typically unnecessary for home fermentation.

Apparent attenuation measures how much of the available sugars were consumed during fermentation, expressed as a percentage. It helps evaluate yeast performance and fermentation completeness.

Fermentation calculators provide good estimates based on gravity readings, but actual alcohol content can vary due to factors like temperature, yeast strain, and measurement accuracy. Professional testing is needed for precise ABV values.

Take your final gravity reading when fermentation appears complete - typically when airlock activity stops and gravity readings are stable over 2-3 consecutive days. This ensures accurate ABV calculations.

Yes, this calculator works for any fermented beverage where you have original and final gravity readings, including wine, mead, cider, and other fermented drinks.

Alcohol by Volume (ABV) measures alcohol as a percentage of total liquid volume, while alcohol by weight measures alcohol as a percentage of total liquid weight. ABV is the standard measurement used on beverage labels.

Fermentation temperature affects yeast activity, fermentation speed, and final alcohol content. Higher temperatures generally increase fermentation rate but may produce off-flavors, while lower temperatures slow fermentation but often improve flavor quality.