This brewing fermentation calculator determines Alcohol by Volume (ABV %), apparent yeast attenuation, and caloric content from hydrometer specific gravity readings. Homebrewers making beer, hard cider, mead, or wine can monitor fermentation health and verify final alcohol percentages by comparing original gravity (OG) prior to pitching yeast against final gravity (FG) at bottling.

### Brewing Formulas and Calculations The calculator computes fermentation metrics using industry-standard brewing equations:

- **Alcohol by Volume (ABV %):** Evaluated using the standard brewing formula: $$\text{ABV} = (\text{OG} - \text{FG}) \times 131.25$$ - **Apparent Yeast Attenuation (%):** Indicates the percentage of fermentable sugars converted into alcohol and CO2: $$\text{Attenuation} = \left[ \frac{\text{OG} - \text{FG}}{\text{OG} - 1.000} \right] \times 100$$ - **Caloric Estimate (per 12 oz serving):** Evaluated using the standard Hall equation combining residual carbohydrates and alcohol energy content: $$\text{Calories} \approx \left[ \frac{1881.22 \times (\text{OG} - \text{FG})}{1.775 - \text{OG}} \right] + 3550 \times (\text{FG} - 1.000)$$

### Worked Numeric Example Suppose a homebrewer crafts an American Pale Ale: - **Original Gravity (OG):** 1.056 - **Final Gravity (FG):** 1.012

**Step-by-Step Calculation:** 1. **Gravity Drop:** $1.056 - 1.012 = 0.044\text{ points}$. 2. **ABV Percentage:** $0.044 \times 131.25 \approx 5.78\%\text{ ABV}$. 3. **Yeast Attenuation:** $[0.044 / (1.056 - 1.000)] \times 100 = (0.044 / 0.056) \times 100 \approx 78.57\%$. 4. **Calories per 12 oz:** Evaluates to approximately **188 kcal**.

### Client-Side Processing Note All calculations execute in client-side JavaScript. No brewing recipes, hydrometer logs, or beer styles are transmitted across any network.