What is the difference between dry and sweet wine?
Quick answer
A dry wine is one where nearly all the grape sugar has been converted to alcohol during fermentation, leaving less than 4 g/l of residual sugar. A sweet wine retains some of that sugar, ranging from off-dry (around 12-45 g/l) to lusciously sweet dessert wines (over 45 g/l).
Detailed answer
When wine people say a wine is 'dry', they do not mean it will leave your mouth parched. Dry simply means the wine contains very little leftover sugar — technically less than 4 grams per litre. Sweet wine, on the other hand, still has noticeable sugar that was not converted to alcohol during fermentation.
Here is what happens in the cellar: yeast eats grape sugar and turns it into alcohol and carbon dioxide. If the winemaker lets the yeast finish the job, you get a dry wine. If they stop the process early — by chilling the tank, filtering out the yeast, or adding sulphur dioxide — some sugar stays behind, and the wine tastes sweet.
Some of the world's greatest sweet wines, like Sauternes or Hungarian Tokaji, start with grapes so incredibly sugar-rich (thanks to a beneficial mould called botrytis) that the yeast simply cannot convert it all before the alcohol level kills them off, usually around 15-16 % ABV. The remaining sugar can exceed 200 g/l — that is about 50 times more than a typical dry wine.
A useful thing to know is that sweetness perception is not just about sugar. Acidity acts as a counterbalance. A German Riesling with 40 g/l of sugar can taste refreshingly crisp if its acidity is high enough, while a low-acid wine with half as much sugar may taste sweeter. Alcohol also plays tricks: a warm, full-bodied red at 14.5 % ABV can feel vaguely sweet even though it contains almost no sugar at all.
Next time you shop for wine, look for terms like 'sec' (dry), 'demi-sec' (off-dry), 'moelleux' (medium-sweet), or 'liquoreux' (lusciously sweet) on French labels. On expertvin.be, every bottle includes a clear sweetness indicator so you always know what to expect.