How it works
How it is calculated
The calculator takes the change in titratable acidity (TA, expressed as tartaric acid, in g/L), multiplies it by the volume and by a factor for each agent: 1.0 for tartaric, 0.89 for malic, 0.85 for citric and 1.2 for lactic. To lower TA, about 0.67 g/L of calcium carbonate or 1.33 g/L of potassium bicarbonate removes 1 g/L.
Units: US labs often report TA in g/100 mL, so 0.65% is 6.5 g/L. If a lab reports TA as sulfuric acid (common in France), multiply by 1.53 to get tartaric.
TA and pH do not move together exactly
As a rule of thumb, 1 g/L of tartaric acid lowers pH by about 0.1, but the real change depends on the wine’s buffer capacity. Some of the added tartaric can also drop out later as potassium bitartrate during cold stabilization. Add part of the amount, measure, and confirm with a bench trial.
Worked example (US units)
500 gal (1,892.7 L) from 5.5 to 6.5 g/L TA with tartaric acid: 1.0 g/L × 1,892.7 L × 1.0 = 1.89 kg, about 4.2 lb.
Questions winemakers ask
Tartaric or malic acid?
Tartaric is the usual choice: it does more per gram and resists microbes. Malic added before malolactic fermentation will be converted by the bacteria.
When does calcium carbonate make sense?
For must or wine with very high acidity. It works mainly on tartaric acid and leaves calcium that can precipitate later, so many winemakers use potassium bicarbonate for small corrections.
Are acid additions allowed?
Yes, in the US and the EU, within limits that depend on the agent and, in the EU, on the wine-growing zone. Check TTB rules (27 CFR part 24) or your local regulations.