Top-down Brew: Estimate Calories and Carbohydrates in a Beer Serving
Method #1: Gravity readings
Method #2: Alcohol by volume
Results
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Notes
This calculator estimates beer Calories (kcal) and carbohydrates. The measured Calories may be slightly different (< 1%) due to differences in protein content, real degree of fermentation, and unfermentable sugars (example: lactose).
Formula: Kcal = (6.9 kcal/g * ABW%) + (4 kcal/g * (RE - ash) where ABW: Alcohol by weight, RE: real extract, and ash = .1 (a commonly used constant for mineral solids; Oxford Companion to Beer, as cited in Stanley, 2021). The left side of the equation estimates the calories from alcohol. The right side calculates calories from unfermented carboydrates.
The formula is expressed for 1 deciliter (i.e., 0.1 L or 100 mL), which seems to be the standard for these calculations.
References
Fix, G.J., and Fix, L.A. (1997). An Analysis of Brewing Techniques, Brewers Publications, p. 141 - 142.
Stanley, S. (2021, October). Counting calories and carbs: Get the skinny on your homebrew. Brew Your Own, p. 32 - 36.