The average bourbon barrel size is 53 gallons, but that doesn't mean a 53-gallon barrel produces 53 gallons of bourbon. If only it were so simple. First of all, it depends on how long it is aged.

Blanton’s bourbon was the first single-barrel product ... Depending on age, a 53-gallon barrel will yield from 100 to 200 bottles. Independent distilleries often have smaller, 30-gallon ...