Regardless of their various shapes, wine bottles have always held about 750 milliliters of wine.
Although 750 milliliters is the standard capacity for wine bottles today, this wasn’t always the case. Historically, wine was stored in many different types of vessels of varying sizes. During the Middle Ages, as the wine trade increasingly fell under governmental regulations, measurements became somewhat standardized. The impetus for this was financial. Governments realized that by standardizing the contents of bottles, wine could be more easily counted. And if it could be counted easily, it could also be taxed easily. But why 750 milliliters exactly? There are several hypotheses. One popular theory holds that 750 milliliters correlates with the average ability of a glass-blower’s lungs to create a bottle in one steady blow.