Yeast Nutrient Calculator
Enter your must volume and its honey load in grams per liter to get the total Fermaid-type nutrient for the batch, split into the classic three staggered additions.
Results
- Per addition
- 0.1 g
- Dosing rate
- 2.2 g per hectoliter (TOSNA 2.1)
Staggered additions
- At pitch
- 0.1 g
- At 24 h
- 0.1 g
- At 48 h
- 0.1 g
- At 1/3 sugar break
- 0.1 g
Degas the must before each nutrient addition - stirring out CO2 right before feeding helps the yeast take up the nitrogen and keeps sulfur compounds from building up.
How the TOSNA dosing works
TOSNA 2.1 steps the dosing rate with the honey load: 1.4 g per hectoliter below 210 g/L honey, 1.8 up to 250, 2.2 up to 290 and 2.6 above that. The total is rate x hectoliters, split into four equal additions: at yeast pitch, at 24 hours, at 48 hours and at the one-third sugar break - the point where a third of the must's sugar has fermented. The schedule front-loads nitrogen while yeast is multiplying fastest and avoids late DAP-style dosing that leaves residual nutrients behind.
The honey load this schedule depends on comes straight from the mead must calculator, which sizes the honey and water for your target ABV and sweetness.
Frequently asked questions
Which nutrients does this schedule apply to?
Organic, complex nutrients such as Fermaid O and Fermaid K, which TOSNA was designed around. If you substitute DAP or generic yeast nutrient, dose by the nitrogen content instead - DAP carries far more YAN per gram, and the same weight would overshoot badly.
What is the one-third sugar break?
The moment the gravity has dropped about a third of the way from OG toward the expected FG - for a must going 1.093 to 0.998, around 1.061. It is the last point where yeast cells can still build healthy membranes, so it is the cutoff for nutrient additions.
Do I need nutrients at all?
Honey is notoriously low in the nitrogen, vitamins and minerals yeast need, unlike malt or fruit juice. Without additions, mead ferments slowly, stresses the yeast and often picks up sulfury off-aromas - nutrients plus good degassing are the single biggest quality lever in mead making.