Few words on a wine label are misunderstood as often as trocken – dry. One drinker expects a wine without any sugar at all; another has just drunk a feinherb (off-dry) Riesling that seemed drier to her than the dry one the night before. Both are right, in their way. For what appears on the label follows a rule of arithmetic, while what arrives in the glass follows the palate.

What the law says

Taste descriptions for wine are regulated uniformly across Europe, in Commission Delegated Regulation (EU) 2019/33, Article 52 in conjunction with Annex III, Part B. Whether a winegrower puts a taste description on the label at all is up to them; the Lower Saxony state office LAVES points to Article 120 of the EU market regulation 1308/2013, which lists it as an optional particular. If they do use one, however, the following limits apply. Residual sugar is counted as the sum of glucose and fructose, and acidity is expressed as tartaric acid.

Dry (trocken): no more than 4 grams of residual sugar per litre. Or no more than 9 grams, provided the total acidity is no more than 2 grams lower than the residual sugar.

Medium dry (halbtrocken): no more than 12 grams per litre. Or no more than 18 grams, provided the residual sugar exceeds the acidity by no more than 10 grams.

Medium sweet (lieblich): more than medium dry allows, but no more than 45 grams per litre.

Sweet (süß): at least 45 grams per litre.

The boundary between medium sweet and sweet deserves a second look. For “sweet”, the regulation says at least 45 grams, whereas the Deutsches Weininstitut (German Wine Institute) simplifies this in its summary to “more than 45 grams”. Going by the wording, a wine with exactly 45 grams could therefore carry either term. For overlaps of this kind, Article 52 stipulates that only one of the two may be chosen.

The formula behind “dry”

It is the second half of the dry rule that is interesting, and it might have been written for Riesling. Put simply, it says: residual sugar may be at most acidity plus 2 grams, but never more than 9 grams.

A few examples. A Riesling with 7 grams of acidity may contain up to 9 grams of residual sugar and still be called dry. With only 6 grams of acidity, the limit is 8 grams. A wine with 5 grams of acidity and 8 grams of sugar, on the other hand, no longer qualifies as dry, because 8 is more than 5 plus 2. And a wine with 10 grams of acidity gains no extra leeway, because 9 grams is the ceiling.

Medium dry works on the same principle. A Riesling with 8 grams of acidity may have 18 grams of sugar and remain medium dry; one with 6 grams of acidity only 16 grams.

What the law does not say matters too: feinherb has no legal definition. The Deutsches Weininstitut places the term somewhere between medium dry and lightly medium sweet. Anyone buying feinherb is therefore relying on the producer’s taste, not on a standard.

Why acidity counts

That the legislator takes acidity into account at all has a sensory rationale. Acidity counteracts sweetness – it buffers it, so to speak. The Swiss wine merchant Delinat offers a vivid example: a Riesling with 6 grams of residual sugar and 8 grams of acidity tastes completely dry. Conversely, a low-acid wine with the same amount of sugar can already come across as distinctly sweetish.

Riesling is the textbook case, since the Deutsches Weininstitut names its „fruchtige Säure“ (our translation: “fruity acidity”) as the grape’s defining feature. A little unfermented sugar often takes the edge off without making the wine seem sweet. That is precisely why the formula exists.

The International Riesling Foundation (IRF) has gone a step further. Its voluntary taste scale is based on the ratio of sugar to acidity: up to 1.0 a Riesling counts as “Dry”, from 1.0 to 2.0 as “Medium Dry”, from 2.1 to 4.0 as “Medium Sweet”, and above that as “Sweet”. It also takes pH into account. A pH of around 3.1 is treated as the norm. At 3.3 or 3.4, a wine moves one category towards sweet, and at still higher values possibly further, because a higher pH means the acidity has a gentler effect. Conversely, a very low pH of 2.9 or below can move a wine one category drier. None of this carries legal weight in the EU, but as a way of thinking about balance it is helpful.

Kabinett is not a sweetness level

The second great misunderstanding concerns the Prädikate, Germany’s ripeness-based quality levels. According to the Deutsches Weininstitut, Kabinett (the lightest Prädikat level, traditionally light and delicate), Spätlese (“late harvest”, the next level up) and Auslese describe the ripeness of the grapes at harvest, measured by must weight. In addition, Prädikat wines may not be enriched, meaning no sugar may be added before fermentation. The Prädikat says nothing about how the finished wine tastes. A Kabinett can be dry or have residual sweetness.

Adding to the confusion, members of the VDP – the Verband Deutscher Prädikatsweingüter, Germany’s association of top estates – now use the Prädikate only for fruchtsüß (fruity-sweet) and edelsüß (nobly sweet) wines. The association adopted the underlying classification in January 2012; for dry estate wines, according to the VDP, the move away from Prädikate applies from the 2019 vintage. Dry VDP wines are labelled “Qualitätswein trocken” and placed in one of the four tiers of the association’s classification: Gutswein (estate wine), Ortswein (village wine), Erste Lage (premier cru) and Große Lage (grand cru). Dry wines from a Große Lage are called Großes Gewächs. Medium-dry and feinherb wines carry no Prädikat at the VDP either. A VDP Kabinett therefore has residual sweetness, whereas a Kabinett from another estate may well have been made dry. In that case, only the taste description on the label will tell you.

How to judge a wine

Even without laboratory figures, sweetness can often be predicted quite well.

Look for the taste description. If the label says trocken or halbtrocken, the limits above apply. If there is no description at all, anything is possible.

Read the alcohol. During fermentation, sugar is converted into alcohol. A Prädikat wine with little alcohol has therefore kept a lot of sugar. Delinat gives the example of a Mosel Kabinett with perhaps 9% abv and 50 grams of residual sugar.

Ask about acidity. Many estates publish analytical data on their website or on a technical sheet. If you know the residual sugar and the acidity, you can apply the formula yourself and work out the ratio in your head.

Trust your palate. The figures are a guide, not a verdict. A medium-dry Riesling from the Saar can seem leaner than a dry one from a hot vintage. In the end it is balance that decides – and so far, there is no regulation for that.