Same must at 15C and 25C - the difference is not days, it is weeks. Enter your wine type, Brix, temperature and yeast to get estimated primary and secondary fermentation time plus a day-by-day monitoring schedule.
12 Brix Must - Estimated Fermentation Time
Same must at 15C and 25C - the difference is not days, it is weeks. Enter your wine type, Brix, temperature and yeast to get estimated primary and secondary fermentation time plus a day-by-day monitoring schedule.
A must at 12 Brix carries a specific amount of sugar that yeast must convert into alcohol and CO2. The higher the reading, the more work for the yeast - and the longer both primary and secondary fermentation take. At 12 Brix with wine yeast at 20 C, the calculator estimates total fermentation time including a day-by-day monitoring schedule that tells you when to check gravity, when to rack off sediment, and when the wine is ready to bottle.
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Same must at 15 C and 25 C - the difference is not days, it is weeks
Temperature shifts fermentation speed dramatically. A grape must at 22 Brix finishes primary fermentation in about 7 days at 20 C with wine yeast. Drop the temperature to 15 C and that number climbs to 8-9 days. Push it down to 12 C and you might wait 13+ days - if fermentation starts at all. This calculator takes your wine type, sugar content, temperature and yeast, then estimates how long primary and secondary fermentation will take. It also builds a day-by-day monitoring schedule so you know when to check gravity, when to rack, and when to bottle.
How to estimate fermentation time - step by step
- Select your wine type - grape, apple, plum, cherry, mead or other. Each fruit has a different baseline fermentation speed.
- Enter the Brix reading - measure your must with a refractometer or hydrometer before pitching yeast. Higher Brix means more sugar and longer fermentation.
- Enter the temperature - the room or fermentor temperature in Celsius. This is the single biggest variable after yeast type.
- Choose your yeast - wine yeast (fastest, cleanest), bread yeast (slower, lower alcohol tolerance) or wild (unpredictable).
- Read your results - primary days, secondary days, total time, potential ABV and a monitoring schedule.
Before and after - how each variable changes fermentation time
The table below shows the same white grape wine (22 Brix, wine yeast) under different conditions. The "before" column uses baseline parameters; the "after" column changes one variable at a time.
| Variable changed | Before (baseline) | After (changed) | Time difference |
|---|---|---|---|
| Temperature 20 C vs 14 C | 35 days | 50 days | +15 days |
| Brix 22 vs 28 | 35 days | 45 days | +10 days |
| Wine yeast vs bread yeast | 35 days | 45 days | +10 days |
| Wine yeast vs wild yeast | 35 days | 63 days | +28 days |
| Temperature 20 C vs 25 C | 35 days | 30 days | -5 days |
Baseline fermentation times by wine type
These numbers assume 20 C, wine yeast and a Brix typical for each style. Your calculator result adjusts these baselines for your actual conditions.
| Wine type | Typical Brix | Primary (days) | Secondary (days) | Total |
|---|---|---|---|---|
| White grape | 20-24 | 5-10 | 21-35 | 4-6 weeks |
| Red grape | 22-26 | 7-14 | 28-42 | 5-8 weeks |
| Apple wine / cider | 10-16 | 5-10 | 14-28 | 3-5 weeks |
| Plum wine | 18-24 | 8-14 | 28-42 | 5-8 weeks |
| Cherry / currant | 18-22 | 10-18 | 35-56 | 6-10 weeks |
| Mead (hydromel) | 24-32 | 14-30 | 60-120 | 3-5 months |
Practical examples
Result: primary 7 days, secondary 25 days, total 32 days (~4.6 weeks). Potential ABV: 13.0%
Result: primary 5 days, secondary 14 days, total 19 days (~2.7 weeks). Potential ABV: 7.1%
Result: primary 11 days, secondary 36 days, total 47 days (~6.7 weeks). Potential ABV: 11.8%
Result: primary 23 days, secondary 97 days, total 120 days (~4 months). Potential ABV: 16.5%
Result: primary 19 days, secondary 65 days, total 84 days (~12 weeks). Bread yeast may stall at 8-10% ABV with 14.2% potential.
FAQ - Frequently asked questions
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Calculator verified by the LiczGrupa.pl team
Content, formulas and results have been reviewed for accuracy and relevance by our team of specialists.
Reviewed by: Natalia Skrzek