Mead · Calculator

Mead 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.

Start calculating Read the guide
Small yeast nutrient doses portioned beside a precision scale and honey must

How to use this calculator

Plan a Fermaid O dose and its early-fermentation additions.

  1. 1

    Set volume and gravity. Enter your batch size and original gravity.

  2. 2

    Choose the intensity. Select light, balanced or high-gravity intensity to suit your batch.

  3. 3

    Read the addition schedule. Check the total grams of Fermaid O and the four scheduled additions.

Stop additions at the one-third sugar break. Refine the plan with repeat gravity readings and observations of fermentation and yeast behaviour.

Live calculator · updates as you type

Your must

Nutrient
TOSNA intensity

Nutrient timing

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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

Total Fermaid O 16.00g
Per gallon 3.20g/gal
1/3 sugar break1.067 SG
Must classStandard traditional range
Schedule 4 equal additions
See your nutrient schedule

Your nutrient addition schedule

WhenAmount
At pitch (0h)4.00 g
24 hours4.00 g
48 hours4.00 g
72h or 1/3 sugar break4.00 g

What to do next

Feed this mead in 4 steps

For your 5 gal batch at an OG of 1.100.

  1. 1

    At pitch

    0 h

    Stir in 4.0 g (1.5 tsp) of Fermaid O, dissolved in a little must.

  2. 2

    Second addition

    24 h

    Add 4.0 g (1.5 tsp). Degas gently first so it does not foam over.

  3. 3

    Third addition

    48 h

    Add 4.0 g (1.5 tsp).

  4. 4

    Last addition

    1/3 break

    When the gravity reaches 1.067, add the last 4.0 g (1.5 tsp).

Free printable

Keep this batch on one page

A batch card made from your numbers, to save as a PDF or receive by email:

  • Your amounts in big type
  • These steps with tick-boxes
  • Key dates to fill in
  • A gravity log for every reading

Optional. You can get your PDF without subscribing. Privacy notice.

Fermaid O reference bands

OG rangeTypical grams/galNotes
1.060-1.0801.9-2.6 g/galHydromel / lower gravity
1.085-1.1052.7-3.6 g/galMost traditional meads
1.110-1.1303.8-4.6 g/galHigher gravity, more stress
1.135+4.8-5.8 g/galStrong meads, oxygen strategy matters

Fermaid O per batch (balanced TOSNA, 4 additions)

OG1 gallon5 gallons
1.0802.6 g (~0.9 tsp), 0.6 g per addition12.8 g (~1.6 tbsp), 3.2 g per addition
1.1003.2 g (~1.2 tsp), 0.8 g per addition16.0 g (~1.9 tbsp), 4.0 g per addition
1.1203.8 g (~1.4 tsp), 1.0 g per addition19.2 g (~2.3 tbsp), 4.8 g per addition
1.1404.5 g (~1.6 tsp), 1.1 g per addition22.4 g (~2.7 tbsp), 5.6 g per addition

Mead nutrient guide

Feed yeast on purpose.

Honey is low in nitrogen, so mead yeast needs help to ferment cleanly. This guide maps must strength into a repeatable nutrient schedule.

Split the total into four equal additions . Stop at the 1/3 break.

How we calculate: Mead methods

Use these reference values to interpret your results

  • Most OG bands

    1.085–1.120

    Where nutrient planning has the biggest payoff.

  • Best rhythm

    4 adds

    A practical stagger for most home mead batches.

  • Stop point

    1/3 break

    Use gravity, not clock time alone.

Scheduling rule

total ÷ 4 early additions

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.

How OG changes nutrient demand

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.

Worked example — 5 gal, OG 1.100, balanced

Gravity points = 100
Per gallon ≈ (100/100) × 3.2 ≈ 3.2 g/gal
Total ≈ 3.2 × 5 ≈ 16 g, split into 4 additions

Use the 1/3 sugar break correctly

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.

At pitch (0h)First addition once the yeast is pitched and rehydrated.
24 hoursSecond addition as fermentation ramps up.
48 hoursThird addition during the most active phase.
72h / 1/3 breakFinal addition — stop here regardless of clock time.

Troubleshooting nutrient plans

Fermentation is sluggish
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.
Fermentation is too aggressive
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.

A TOSNA yeast nutrient calculator for mead

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.

FAQ

Mead nutrient planning questions

Common questions about nutrients, the 1/3 break, and dosing by gravity.

Why does mead need nutrients?
Honey is low in yeast-assimilable nitrogen, so nutrients reduce stress and help cleaner fermentation.
What is the 1/3 sugar break?
It is a common point where nutrient additions stop to avoid late-stage off-character.
Can I use liters?
Yes, the calculator supports gallons and liters.
Does this replace oxygen management?
No. Nutrients, oxygen timing, temperature, and healthy pitch rates all matter.
Is this only for Fermaid O?
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.
When do you add Fermaid O to mead?
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.
How many tsp of Fermaid O per gallon of mead?
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.
How many teaspoons or tablespoons of Fermaid O are in an ounce?
Fermaid O is light and fluffy, about 2.5–3 g per level teaspoon. An ounce (28 g) is therefore roughly 10 teaspoons, or about 3½ tablespoons. Weigh it when you can, because how firmly the spoon is packed changes the dose a lot.
Should I change dose for high gravity?
High OG musts may need a higher schedule, which is why intensity mode is included.

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