Calculator Inputs
Enter measured values, or leave final gravity blank to predict it from attenuation.
Formula Used
Standard ABV: ABV = (OG − FG) × 131.25
Advanced ABV: ABV = [76.08 × (OG − FG) / (1.775 − OG)] × [FG / 0.794]
Predicted FG: FG = 1 + [(Adjusted OG − 1) × (1 − Attenuation ÷ 100)]
Sugar gravity boost: Points = Sugar lb × PPG ÷ Gallons
Priming boost: Extra ABV ≈ Priming sugar g/L × 0.0648
Apparent attenuation: [(OG − FG) ÷ (OG − 1)] × 100
How to Use This Calculator
- Enter the original gravity from your hydrometer or refractometer notes.
- Add final gravity if fermentation is complete.
- Leave final gravity blank when you want a prediction from attenuation.
- Enter batch volume, sugar additions, and priming sugar.
- Use temperature correction when gravity readings were taken warm or cold.
- Press the calculate button to view ABV, attenuation, calories, and servings.
- Use the graph to compare different attenuation outcomes.
- Download CSV or PDF records for your brew log.
Example Data Table
| Brew Type | OG | FG | Attenuation | Volume | Approx ABV |
|---|---|---|---|---|---|
| Light Ale | 1.038 | 1.010 | 73.7% | 20 L | 3.7% |
| Pale Ale | 1.052 | 1.012 | 76.9% | 19 L | 5.3% |
| Strong Stout | 1.078 | 1.018 | 76.9% | 18 L | 8.0% |
| Dry Cider | 1.060 | 1.002 | 96.7% | 23 L | 7.6% |
Predicting Brew Alcohol Level
Why Alcohol Prediction Matters
A brew alcohol level calculator helps you plan strength before serving. It also helps you compare batches with more control. Small gravity changes can make a clear difference. A few points of sugar can raise alcohol. A lower final gravity can also raise alcohol. That is why gravity tracking is important.
Gravity Gives the Main Signal
Original gravity shows the amount of dissolved fermentable material. Final gravity shows what remains after fermentation. The gap between both readings estimates alcohol formation. A larger gap usually means a stronger drink. This tool uses both the common formula and an advanced formula. The advanced formula is useful for stronger recipes. It can give a more realistic estimate.
Attenuation Helps With Predictions
Sometimes final gravity is not known yet. In that case, attenuation can predict the ending point. Yeast strain, temperature, recipe style, and mash profile affect attenuation. Dry brews often finish lower. Sweet brews often finish higher. This calculator lets you test several attenuation levels. The graph shows how strength may change.
Sugar and Packaging Effects
Extra fermentable sugar can raise original gravity. Priming sugar can also add a small alcohol boost. The boost is usually modest. Still, it should be included for better records. Packaging loss is also useful. It shows how many servings may remain after transfer. This helps with planning bottles, cans, or kegs.
Better Brew Records
Consistent notes improve future batches. Record gravity, volume, sugar, temperature, and attenuation. Then compare the predicted result with the actual result. Over time, your recipes become easier to repeat. Your yeast performance becomes easier to understand. The download options make this record keeping simple.
FAQs
1. What does this calculator predict?
It predicts brew alcohol level using gravity, attenuation, sugar additions, volume, temperature correction, and priming sugar. It also estimates calories, servings, and packaged volume.
2. Can I use it before fermentation ends?
Yes. Leave final gravity blank. The calculator will estimate final gravity from your expected attenuation percentage and then predict the likely alcohol level.
3. Which ABV formula is shown?
The page shows a standard formula and an advanced formula. The final headline result uses the advanced formula plus the estimated priming sugar boost.
4. Why add hydrometer temperature correction?
Hydrometers are calibrated for a set temperature. Warm or cold samples can shift readings. Correction helps improve the original and final gravity estimates.
5. What is sugar potential PPG?
PPG means points per pound per gallon. It estimates how much a fermentable sugar raises gravity. Table sugar is often near 46 PPG.
6. Does priming sugar change alcohol level?
Yes, but usually only a little. Bottle conditioning sugar ferments into carbon dioxide and alcohol, so the calculator adds a small ABV boost.
7. Why does attenuation affect the result?
Higher attenuation means more sugar was fermented. That usually lowers final gravity and raises alcohol level. The chart shows this effect clearly.
8. Can I download my calculation?
Yes. After calculating, use the CSV button for spreadsheet records or the PDF button for a printable brew log summary.