What actually is must weight?
Anyone interested in wine will, sooner or later, come across the term ‘must weight’. But what does it actually mean? In short, for winemakers, the must weight is a sort of preview of the finished wine.
Even before fermentation, it reveals a great deal about the future quality and alcohol content.
Water vs. grape juice: What exactly is being measured?
In Germany (and also in Switzerland), must weight is usually measured in degrees Oechsle (°Oe). The principle behind this is simple: it indicates how much heavier a litre of grape juice (the must) is compared to a litre of pure water. As it is primarily the fructose that makes the juice dense and heavy, the following applies: more sugar = higher must weight. And as the yeasts later convert this sugar into alcohol, the winemaker essentially knows how full-bodied the wine will be. This is measured either using a small handheld optical device (a refractometer) or a glass tube known as a must hydrometer.
The riper the grape, the higher its value
With every sunny day on the vine, the grapes accumulate more sugar. The must weight increases. Sometimes nature even lends a helping hand with a little trick: so-called noble rot (caused by the fungus Botrytis cinerea). This fungus makes the skin of the berries wafer-thin and permeable. When the sun shines, the water in the berry evaporates and the sugar becomes extremely concentrated. When we sit down to enjoy the wine, we needn’t worry too much about the Oechsle degrees. It can be more interesting to look at the information on the residual sugar content. We list this on our wine list once we have received the details from the winemakers’ wine reports, which is almost always the case.
The basis of predicates
Shortly before, or rather during, the 2026 grape harvest, we were guests at a winegrower’s. He actually had the Oechsle degrees for all his grape varieties in his head at that moment and recited them with satisfaction. For winegrowers, the must weight is of extraordinary importance: the higher the must weight, the higher the subsequent quality or classification level (such as Spätlese, Auslese or Eiswein). As each grape variety requires different conditions and the weather varies from place to place, each of the 13 German wine-growing regions has its own binding minimum values for must weight. And this is also the case in the northernmost of the 13, Saale/Unstrut.
The german quality classifications will remain, under certain conditions. However, from the start of 2026, Germany will be moving away from the traditional, Germanic system (quality based on must weight/sugar content) and switching to the Romance, origin-based quality system (also known as the terroir principle). It is difficult for us to make sense of this at the moment; we are looking into it in more detail and, once we have a clear overview, we will publish it here.
