The measure of how much a vineyard produces. In general, very high yields are associated with low-quality wine, and low yields are associated with high-quality wine. However, the relationship of yield of grapes to wine quality is extremely complex and not linear. Thus, a yield of 2 tons per acre does not necessarily produce better wine than a yield of 3 tons per acre, which doesn’t necessarily portend better wine than if the yield were 4 tons per acre. Every vineyard is different, and yield must always be considered in light of multiple other factors, including the variety of grape, the type of CLONE, the age of the vine, the particular ROOTSTOCK, and the TERROIR. In Europe, yield is measured in hectoliters per hectare (one hectoliter equals 26.4 gallons; one hectare equals 2.47 acres). The unofficial French dictum is that great red wine cannot be made from yields of more than 50 hectoliters per hectare. In the United States, yield is generally measured in tons of grapes per acre. Roughly speaking, 1 ton per acre equals 15 hectoliters per hectare. Yields in the United States can range from less than 1 ton per acre to 10 or more. This said, the way yield is thought about in the United States is changing as a result of new vineyards, many of which are now planted so that the vines are much more closely spaced than they were in the past. With such vineyards, viticulturists talk of pounds of grapes per vine, rather than tons per acre.