How many grapes in a bottle?

A popular question is how much fruit is needed to a barrel or more tangiblely, a bottle. The short answer is one bottle = ~2.75lbs of grapes. The long answer is provided below.

First off, vineyards vary in the spacing between the rows and between the individual vines. Some are close and compact (high density) and others more spaced apart. Also, depending upon the age and variety, some varietals are more productive or have larger clusters of fruit and some yield more juice per pound of fruit.

Here are rough averages:
One pound of grapes =~4.5 clusters (or bunch)
One cluster =~40-60 grapes
One ton= ~9000 clusters

I usually make 1-2 tons of each wine which translates to:
One ton of grapes = 2 barrels
2 barrels= ~720 bottles= ~60 cases
One case= 12 bottles

One bottle = ~2.75lbs of grapes=11 clusters= 440-660 grapes

Most of the vineyards I work with get between 2-3.5 tons per acre.

Source: Professional Friends of Wine