Free tools for winemakers
Acid adjustment calculator
Raise or lower titratable acidity
Tartaric acid to add
Type the volume, the current TA and the target.
The usual choice. Some of it drops out as cream of tartar during cold stabilization, so TA can end a little below the target.
Past a legal limit.
A big drop. Lowering TA by more than about 2 g/L with calcium carbonate or potassium bicarbonate can taste salty or flat and push the pH too high. Consider blending with another wine, or lower it in steps.
Bench trial first. TA doesn't tell you the pH: the same addition moves pH differently in every wine. Treat a small measured sample, check its pH and taste, then scale up.
Check your local rules. Most wine regions limit acid additions and deacidification. In the EU, acid may be raised by at most 4 g/L and a wine lowered by at most 1 g/L (both as tartaric), and the same product may not be both acidified and deacidified. The US caps fixed acidity at 9 g/L as tartaric after adding acid.
How do we calculate this?
The exact formulas used in this tab:
What this calculator does
Works out how much acid to add to raise a must or wine’s titratable acidity (TA) to a target, or how much potassium bicarbonate or calcium carbonate to add to lower it.
- The acid can be tartaric, malic, citric or lactic. Type TA as tartaric or as sulfuric.
- In a warm climate like Israel’s, grapes often ripen with too little acid, so adding acid is the everyday correction and lowering it is rarer.
- It works with TA only: it can’t tell you what the pH will be.
The formula
TA in g/L as tartaric; as sulfuric × 1.5306 firstΔTA = |target − current|Raise: acid (g) = ΔTA × volume L × (equivalent weight ÷ 75.04)Equivalent weights: tartaric 75.04, malic 67.04, citric 64.04, lactic 90.08Per 1 g/L of TA: tartaric 1 g/L, malic 0.893, citric 0.853 (monohydrate 0.933), lactic 1.2Acids are pure: divide lactic by its strength (e.g. 0.8 for an 80% solution)Lower: potassium bicarbonate (g) = 0.9 × ΔTA × volume LLower: calcium carbonate (g) = 0.67 × ΔTA × volume LBoth are rules of thumb for TA around 8–10 g/L; the target can’t go below 3 g/LSources: AWRI Technical Note TN14 (acid equivalents); AWRI, "What is chemical deacidification?"TA only: pH change cannot be worked out from TA
Worked example
Raising acidity with tartaric
- 1,000 L of must
- TA now: 5 g/L (as tartaric)
- Target: 6.5 g/L
- How much to raise TA 6.5 − 5 = 1.5 g/L
- Tartaric acid for the tank 1.5 g/L × 1,000 L = 1.5 kg
- For a 100 mL bench trial 1.5 g/L × 0.1 L = 150 mg
Add 1.5 kg of tartaric acid
The same rise with malic or lactic
- 1,000 L of must
- Raise TA by 1.5 g/L
- Malic acid per gram of tartaric 67.04 ÷ 75.04 = 0.893
- Malic acid for the tank 1.5 g/L × 1,000 L × 0.893 = 1.34 kg
- Pure lactic acid for the tank 1.5 g/L × 1,000 L × 90.08 ÷ 75.04 = 1.801 kg
Add 1.34 kg of malic acid, or 1.801 kg of pure lactic acid
Malic acid gives more acidity per gram than tartaric, so you need less of it; lactic gives less, so you need more.
Lowering acidity
- 1,000 L of wine
- TA now: 8 g/L
- Target: 7 g/L
- How much to lower TA 8 − 7 = 1 g/L
- Potassium bicarbonate 1 g/L × 1,000 L × 0.9 = 900 g
- Or calcium carbonate 1 g/L × 1,000 L × 0.67 = 670 g
Add 900 g of potassium bicarbonate or 670 g of calcium carbonate
Questions
Why add acid at all, and why tartaric?
In warm regions such as Israel, grapes often reach ripeness with low acid and a high pH, which leaves the wine flat and less protected. So acid is added far more often than it is lowered. Tartaric acid is the usual choice: it is the grape’s own main acid, and bacteria don’t break it down. Malic and lactic acid are also used. Citric acid is added only after malolactic fermentation, and the EU does not allow it to raise acidity.
How much will the pH change?
The calculator can’t tell you. pH depends on how strongly each wine resists change — its potassium and its other acids — so the same TA change moves pH differently in every wine. Run a bench trial first: treat a small measured sample at the planned rate, check pH and taste, then scale up. Some added tartaric acid can also drop out as cream of tartar during cold stabilization, so the TA you end up with can be lower than planned.
How far can I lower acidity?
The calculator uses 0.9 g/L of potassium bicarbonate or 0.67 g/L of calcium carbonate for each 1 g/L drop in TA, the practical figures published by the AWRI. Keep a drop to about 2 g/L or less: more can taste salty or flat and push the pH too high. The target can’t go below 3 g/L, because the factors only hold near 8–10 g/L. The law limits it too. The EU allows a wine to be lowered by at most 1 g/L and raised by at most 4 g/L (as tartaric). The US does not allow fixed acidity below 5 g/L after potassium bicarbonate or 4.79 g/L after calcium carbonate, nor above 9 g/L after adding acid. The calculator warns when a change passes one of these. Check your local rules before adding acid or deacidifying.
EU: Regulation (EU) No 1308/2013, Annex VIII, as amended by Regulation (EU) 2021/2117. US: 27 CFR 24.246 (deacidifying), 27 CFR 24.182 (adding acid).
My lab gives TA as sulfuric acid. Does that matter?
No. Choose “Sulfuric acid” next to the current TA. The calculator converts it to tartaric by multiplying it by 1.5306, so the amounts come out the same.
Guides that use this calculator
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Malolactic fermentation: how to do it and when it's done
Malolactic fermentation turns malic acid into lactic, cutting TA by 0.56 g/L per g of malic. Run it at 18–22 °C with no SO₂; it's done below 0.1 g/L.