Mead · TOSNA Nutrient Calculator
Plan a practical TOSNA-style yeast nutrient schedule from your batch size and original gravity — total grams plus a staggered addition plan, for Fermaid O, Fermaid K, or DAP.
5 gal · OG 1.100 · balanced
≈ 16 g Fermaid O
Split the total into four equal additions. Stop at the 1/3 break.
Live calculator · updates as you type
A practical TOSNA-style estimate for Fermaid O. Stop nutrient additions once you pass the 1/3 sugar break, and always combine with temperature control, early oxygenation, and healthy yeast pitch rates.
Fermaid O schedule
Fermaid O reference bands
Honey is poor in yeast-assimilable nitrogen, so mead needs a yeast nutrient schedule to ferment cleanly. This yeast nutrient calculator builds a TOSNA-style plan around Fermaid O by default, and the toggle switches it to Fermaid K or DAP — both stronger per gram, so the calculator drops the dose and stops the additions by the 1/3 sugar break. Pair any inorganic nutrient with an organic base and good temperature, oxygen, and pitch-rate practice.
Mead nutrient guide
Honey is low in nitrogen, so mead yeast needs help to ferment cleanly. This guide maps must strength into a repeatable nutrient schedule.
Where nutrient planning has the biggest payoff.
A practical stagger for most home mead batches.
Use gravity, not clock time alone.
Front-loading the total across four additions before the 1/3 sugar break usually improves yeast performance and flavour cleanliness compared to a single dose.
Enter your batch size and original gravity, then choose a light, balanced, or high-gravity intensity. The calculator returns the total grams of Fermaid O plus a four-step addition schedule spread across the early fermentation.
Use it as a process baseline and refine over time by watching fermentation speed, yeast behaviour, and repeat gravity readings. Nutrient planning is one lever among several — pair it with the rest of your process.
Higher original gravity generally means greater yeast stress and higher nutrient demand. A dense, high-sugar must pushes the yeast harder, so it needs more nitrogen to ferment cleanly. Lower-gravity meads usually need less.
Tying the dose directly to OG keeps nutrient planning anchored to real must strength instead of rough guesswork. That is why the calculator reads OG rather than asking you to pick a fixed amount.
The 1/3 sugar break is a common stop point for nutrient additions — the gravity where roughly a third of the sugar has fermented. Front-loading nutrients before this point supports yeast health during the most active phase and avoids feeding nitrogen late, which can cause off-character.
Track the break with gravity checks rather than time alone. The clock is a rough guide; the hydrometer tells you where the ferment actually is.
If fermentation drags, review pitch rate, oxygen timing, and temperature alongside your nutrient totals. A stalled or sluggish ferment is rarely a nutrient problem alone — the early oxygen and a healthy pitch matter just as much.
If fermentation is too aggressive or throws heat, reduce the intensity next batch and compare results in your log. Over a few batches you will learn the schedule that keeps your yeast happy without overdriving it.
Track nutrient additions, gravity checks, and tasting notes for every batch in one printable sheet.
Common questions about nutrients, the 1/3 break, and dosing by gravity.
Honey is low in yeast-assimilable nitrogen, so nutrients reduce stress and help cleaner fermentation.
It is a common point where nutrient additions stop to avoid late-stage off-character.
Yes, the calculator supports gallons and liters.
No. Nutrients, oxygen timing, temperature, and healthy pitch rates all matter.
No. Fermaid O is the default TOSNA schedule, but you can switch the nutrient toggle to Fermaid K or DAP. Both carry more nitrogen per gram than Fermaid O, so the calculator lowers the dose and splits it into three additions that finish by the 1/3 sugar break.
The TOSNA method spreads Fermaid O across four equal additions: at pitch, then roughly 24, 48, and 72 hours in, stopping by the 1/3 sugar break (when about a third of the sugar has fermented). Adding nutrients past that point can leave harsh, off-character notes. Fermaid K and DAP should finish even earlier, by the 1/3 break at the latest.
Roughly 1 to 1.5 teaspoons of Fermaid O per gallon total for a standard traditional mead, split across the additions — about 2.5–3 g per teaspoon. The calculator gives the exact grams for your OG and batch size; weigh it with a scale for accuracy, since teaspoon volumes vary with how packed the powder is.
High OG musts may need a higher schedule, which is why intensity mode is included.