How to Calculate ABV from Specific Gravity

Whether you are fermenting your first batch of cider or perfecting a complex stout, knowing exactly how to calculate ABV homebrew is a foundational skill. By tracking the sugar density of your liquid before and after fermentation, you can easily determine the final alcohol content.

Using a Hydrometer for Beer and Mead

If you are wondering how is ABV calculated, the process starts with a hydrometer. This simple glass tool measures the density of your liquid relative to water. When asking how to calculate ABV with hydrometer, you must take two readings: your Original Gravity (OG) before adding yeast, and your Final Gravity (FG) when fermentation is complete. As yeast eats the sugar and creates alcohol, the liquid becomes less dense.

For standard brewing, the fundamental formula for how to calculate ABV beer is: (OG - FG) × 131.25 = ABV%. However, if you want to know how to calculate ABV in mead or high-gravity wines, a slightly different "Advanced" formula is required to account for the changing density of high-alcohol environments.

Automate Your Brewing Math

Instead of doing the math by hand, the fastest way to get your answer on how to calculate ABV is to use a digital tool. Head over to our main ABV Calculator, select "Brewing Mode," and punch in your specific gravity readings. The engine will instantly calculate your final alcohol percentage and apparent attenuation.