For centuries it was actually illegal to sell alcohol in the bottle. There were so many different bottle types—and sizes of alcohol bottles variations—that it was far too easy to cheat. Honest merchants measured out wine from their barrels into containers that customers supplied themselves.
While there are a number of theories, no one seems to know for sure why 750 ml became the preferred size for alcohol bottles. The use of glass bottles for alcohol dates back to as early as the 17th century. However, during this period when there was less travel from region to region, each area developed their own style, size, and shape of bottle.
It wasn’t until the 1970s that there became a more uniform type of alcohol bottle. As exporting and importing wine became more common in Europe and the United States, different size for alcohol bottles became increasingly problematic for customs and taxing. To make the importation and taxation process more efficient, a standard size was needed.
As a result, in 1975 European legislation required that alcohol could only be sold in certain sized containers, and of those, the 750 ml became the preferred size for alcohol bottles. In 1979, to help with the process and seemingly as part of the United States’ efforts to move towards the metric system, there was a mandate that wine bottles must contain 750ml of wine. Not surprisingly, this quickly became the global standard because it made exporting to the United States easier.
This history helps to understand how the 750ml bottle became the standard size for alcohol bottles, but it still doesn’t explain why. There are a number of theories attempting to explain this unusual size: