In winemaking, there are two measures that are referred to commonly as yield.
The first is the quantity of grapes produced per vineyard area – so typically tonnes or kilograms per hectare.
The second is the volume of wine produced per vineyard area (more common in Europe) – so typically hectolitres per hectare.
There is not a direct relationship between the two (that is, you cannot say a yield of x kilograms per hectare translates to y hectolitres of wine per hectare) as the volume of wine produced is dependent on many things, not least the grape variety.
Lower yields are typically associated with higher quality wines and attract higher prices.
