Wine Acid Adjustment Calculator

Acidity is what keeps wine from tasting like fruit juice. It carries freshness, it holds colour in reds, it slows spoilage organisms, and it is most of what makes a wine last. Wine pH runs from about 3.0 to 4.0, and most dry table wine is happiest between 3.3 and 3.6.

Why tartaric acid? Tartaric is the main acid in grapes, and unlike malic it is stable. Malic gets eaten by malolactic bacteria and converted to something much softer, so a wine acidified with malic can lose the correction later without warning. Citric is worse still, since bacteria turn it into acetic acid, which is vinegar. Tartaric stays put.

Approximate dose: roughly 1 g/L of tartaric acid per 0.1 of pH. Treat that as an order of magnitude rather than a prediction. The real figure depends on the wine’s buffering capacity, which is mostly a function of its potassium level, and a high-potassium wine can swallow 2 g/L and barely move.

Guideline amounts:

• To lower pH by 0.1: add about 1 g/L
• To lower pH by 0.2: add about 2 g/L
• To lower pH by 0.3: add about 3 g/L, and taste at every step

Maximum addition: past about 4 g/L, tartaric starts dropping out as potassium bitartrate, the cream-of-tartar crystals you find under a cork. Two things then go wrong at once: you lose part of the acid you paid for, and because each crystal removes a potassium ion as well, the pH can end up moving less than you calculated, or occasionally the wrong way entirely. Big corrections are better done in two additions weeks apart than in one.

Titratable acidity is the other half of the story. pH tells you how strong the acid is; TA tells you how much of it there is, and TA is what you actually taste. A gram of tartaric per litre raises TA by roughly 1 g/L whatever it does to pH. Most dry table wine sits at 5.5 to 7.5 g/L TA, so if a pH correction would push TA past about 8, the wine will taste sharp regardless of what the meter says.

The opposite problem. For a wine that is too acidic, use potassium bicarbonate or calcium carbonate, in small doses, measuring as you go. Both raise pH but leave a taste of their own if overdone, and calcium in particular can throw crystals months later.

Always measure before and after. Add half the calculated dose, stir it right through, give it a few minutes, then re-measure and decide. Acid cannot be taken back out.