Fermentation have finished in two beers of mine. I entered the measured Brix and SG in the excel data sheet which calculated an estimated ABV of 6.3 based on original Brix of 13.5 and final Brix of 6.9 in one of the beers (ABV 5.3 in the other - see below). I entered the same readings in the brew session calculater and got an ABV of 3.54 (see further below). Why do these calculations come up so different? Excel spreadsheet: Refractometer Final Gravity Calculator from http://seanterrill.com Version 3.0 Fields in red are required. Wort correction factor: 0.91 Fields in green are optional. (default: 1.04) Refractometer FG Correlations Batch # Name/Description Orig °Brix Final °Brix OG Hydro FG Old Cubic New Cubic New Linear Attenuation App. Atten. ABV 1 Sierra Nevada 13.5 6.9 1.060 1.0110 1.0111 1.0139 1.0138 66.4% 81.0% 6.3% 2 Märzen 13.8 8.2 1.062 1.0200 1.0193 1.0190 1.0185 54.5% 66.5% 5.3% Brew session: Alcohol and Attenuation: ABV: 3.54% Apparent Attenuation: 49.7% Actual FG: 6.9 °P Calories per 355mL: 186 ABV Calculations FAQ ?