The standard serving size for a shot of liquor is 1.5 ounces. This measurement has become widely accepted and is used in most bars and restaurants in the United States. The 1.5-ounce shot allows bartenders to pour a consistent amount of alcohol for cocktails or straight drinks, which helps with maintaining the balance of flavors in a drink and standardizes serving sizes across different venues.
While other options represent various amounts of liquor, they do not align with common bartending practices. For instance, a 1-ounce shot is less than the standard amount and might not provide enough alcohol for typical mixed drinks or neat servings. Conversely, servings larger than 1.5 ounces, such as 2 ounces or 3 ounces, are often considered oversized shots and may not adhere to the standards of responsible serving or drink pricing, which can affect consumer perception and overall experience. Therefore, 1.5 ounces remains the ideal standard for a shot of liquor in the bartending industry.