ABV Calculator (Homebrew & Cocktails)
Calculate alcohol by volume for homebrewed beer, wine or cider from original and final gravity — or the strength of a mixed cocktail from its ingredients.
How to use
- 1For brewing, enter the original gravity (OG) before fermentation and final gravity (FG) after.
- 2For a cocktail, list each ingredient as 'ml abv%' and choose the dilution from shaking or stirring.
How it's calculated
Brewing: ABV ≈ (OG − FG) × 131.25. Cocktail: ABV = Σ(volume × abv) ÷ total volume after dilution (shaken ≈ +25% water, stirred ≈ +20%).
Frequently asked questions
How accurate is the (OG − FG) × 131.25 formula?
Very close for normal-strength beers. Above about 8% ABV, the 'alternate' formula gives slightly higher, more accurate values.
What is gravity?
The density of the wort or must relative to water, measured with a hydrometer — sugar makes it heavier; fermentation lowers it.
Why does dilution matter for cocktails?
Ice melts into the drink while shaking or stirring, adding 20–25% water and lowering the strength.