Tool
ABV & attenuation calculator
Enter your original and final gravity to estimate alcohol by volume (ABV) and apparent attenuation — for beer, cider, mead and wine.
Alcohol by volume
5.3%Apparent attenuation
80%How it's calculated
ABV is estimated as (OG − FG) × 131.25, a standard approximation for typical gravities.
Apparent attenuation is (OG − FG) ÷ (OG − 1) × 100 — the share of sugars the yeast consumed.
For high-gravity worts or spirit washes these approximations drift; use a more precise formula or a hydrometer/refractometer correction where accuracy matters.
fermt records OG, FG, ABV and yield behind every batch, so your numbers, labels and reports all draw from the same data. Start free trial.