This calculator generates a staggered nutrient addition schedule for your fermentation. It prioritizes organic nitrogen (Fermaid O) before supplementing with inorganic sources (Fermaid K and DAP) to meet your yeast’s specific Yeast Assimilable Nitrogen (YAN) requirements while strictly enforcing manufacturer dosage limits and combined product safety caps.
Step 1: Enter Your Must Data
Volume & Unit: Total volume of your must (in liters or US gallons).
Starting Brix: The initial sugar concentration. This dictates the total target YAN requirement.
Measured must YAN: The baseline assimilable nitrogen already present in your juice or must (enter 80 if unknown for wine grapes, or 0 for mead/cider with no natural YAN).
Step 2: Set Yeast Parameters
Yeast Nitrogen Need: Consult your yeast strain's specifications (Low, Medium, or High requirement). See the Scott Labs Yeast Guide for strain profiles and nutrient requirements.
Dry Yeast Pitch: Amount of dry yeast pitched per hectoliter (typically 25 g/hL). This determines the Go-Ferm Protect rehydration dosage (~1.25× yeast pitch, minimum 31.3 g/hL). As a rule of thumb, use 1 g dry yeast per gallon of wine (~14 lbs of pre-destemmed grapes yield ~1 gallon of finished wine).
Step 3: Fermentation Conditions
Hard Conditions: Check this box if potential alcohol exceeds 14%, fermentation temperature is extreme (<16°C or >28°C), or high wild microflora is suspected. This increases the cumulative Fermaid limit (Fermaid O + Fermaid K) from 40 g/hL to 50 g/hL and the individual Fermaid K cap from 25 g/hL to 50 g/hL.
Prolonged Fermentation Under 12°C (54°F): Check this for cold fermentations. It increases the baseline target YAN by 20% to mitigate cold-induced cellular transport stress.
Step 4: Staggered Addition Schedule & Cap Rules
Additions follow a strict four-phase allocation protocol to optimize yeast kinetics without exceeding autolyzed solid or inorganic salt thresholds:
Phase 1: Rehydration (Go-Ferm Protect)
Dissolve Go-Ferm Protect in rehydration water prior to yeast pitching. Note: Go-Ferm contributes 0 mg N/L YAN to the must calculation.
Phase 2: End of Lag Phase (8–24 hrs / 2–3° Brix Drop)
Add the first dose of organic nitrogen (Fermaid O) up to a maximum of 20 g/hL to build clean, healthy biomass.
Phase 3: 1/3 Sugar Depletion (~16° Brix for a 24° Brix must)
Fermaid O (Dose 2): Add up to 20 g/hL, keeping total Fermaid O within its 40 g/hL individual limit.
Fermaid K: If a YAN deficit remains, Fermaid K is added only up to the remaining allowance under the cumulative Fermaid cap (40 g/hL standard, or 50 g/hL in Hard Conditions).
(Example: If 40 g/hL of Fermaid O was allocated, Fermaid K is capped at 0 g/hL under standard conditions).
Phase 4: Straight DAP Addition (1/3 Sugar Depletion)
If a deficit remains after reaching the cumulative Fermaid limit, pure DAP is allocated up to an absolute ceiling of 40 g/hL (~80 mg N/L YAN). Do not add any nitrogen supplements past 1/3 sugar depletion or below 5° Brix.
Step 5: Save or Print Your Schedule
Download HTML: Click to export a standalone, fully functional offline copy of the calculator pre-filled with your current batch parameters and calculation tables.
Printing: Browser security prevents direct print triggers from within an embedded frame. To print, open your downloaded HTML file and print from your browser, or press Ctrl + P (Windows) / Cmd + P (Mac) directly on the page.
Important Safety Rules & Unmet Shortfalls
Combined Fermaid Cap: Total Fermaid products (Fermaid O + Fermaid K combined) are limited to 40 g/hL (50 g/hL under Hard Conditions) to prevent excessive autolysate solids and thiamine accumulation.
DAP Cap: Straight DAP is capped at 40 g/hL to prevent ammonia toxicity, excessive fermentation heat, and harsh chemical bitterness.
Unmet YAN Shortfall Warning: If your must has an extreme deficit where target YAN cannot be met within the 40 g/hL combined Fermaid and 40 g/hL DAP caps, the calculator displays an Unmet YAN Shortfall banner. Do not exceed product safety caps. Manage remaining nitrogen stress by aerating during the first 48 hours and implementing strict temperature management to prevent sluggish or stuck fermentations.
Updated: 10/14/2026 M.Orton