Is there sugar in wine?
Quick answer
Yes. A dry wine typically contains under 4 g of residual sugar per litre (about 0.6 g per glass). Off-dry wines contain 4-12 g/L, and sweet wines can exceed 45 g/L — roughly 2 sugar cubes per glass.
Detailed answer
The sugar in wine is called 'residual sugar' — grape sugar (glucose and fructose) that the yeast did not convert to alcohol during fermentation. In a dry wine, fermentation is virtually complete, leaving very little sugar behind.
EU regulations define the following categories for still wines: dry (under 4 g/L residual sugar, or up to 9 g/L if total acidity is high), off-dry (4-12 g/L), medium-sweet (12-45 g/L), and sweet (over 45 g/L). For sparkling wines, thresholds differ: brut nature (0-3 g/L), extra-brut (0-6 g/L), brut (0-12 g/L), extra-dry (12-17 g/L), sec (17-32 g/L), and demi-sec (32-50 g/L).
Even a 'dry' wine contains a small amount of sugar. However, 2-4 g/L translates to just 0.3-0.6 g per 150 ml glass — a negligible caloric contribution (1.2-2.4 kcal).
Some popular wines contain far more sugar than their image suggests. A Moscato d'Asti can reach 120 g/L, a Sauternes 80-180 g/L, and certain German Riesling Spatlese 40-80 g/L. Even some 'extra dry' Prosecco contains 12-17 g/L.
For those watching their sugar intake, brut nature or extra-brut sparkling wines and dry reds from warm climates (where fermentation typically runs to completion) are the best choices.