As a sommelier and brewer, I can tell you that the size of a shot can vary depending on where you are in the United States. In Utah, for example, a shot is officially defined as 1.5 US fluid ounces, which is equivalent to about 44.4 milliliters. This specific measurement is unique to Utah and may not be applicable in other states.
In most other parts of the U.S., a standard shot is generally considered to be between 1.25 to 1.5 US fluid ounces, which is approximately 37 to 44 milliliters. This range is commonly accepted, but it's important to note that there is no universally recognized official size for a single shot. Different establishments and regions may have their own interpretations.
To give you a more personal perspective, I've encountered various shot sizes throughout my career. In certain cocktail bars, especially those that focus on craft cocktails, shots may be smaller to allow for a greater emphasis on the overall balance of flavors. On the other hand, in more casual settings or during special events, shots may be poured more generously.
It's worth mentioning that shot sizes can also differ depending on the type of spirit being poured. Some spirits, such as high-proof liqueurs or certain whiskeys, may be served in smaller quantities to account for their higher alcohol content. This ensures that the drinker can fully appreciate the flavors without being overwhelmed by the alcohol.
To summarize the information above, the size of a shot can vary, but a common range in the U.S. is between 1.25 to 1.5 US fluid ounces (37 to 44 milliliters). However, it's important to remember that there is no universally defined standard for a shot size and it can vary depending on the establishment and the type of spirit being served.