The amount of calories in hard alcohol is approximately 100 per shot, which is 2 to 3 ounces. When mixed in a cocktail, calories can increase substantially.
Calories will vary depending upon which alcohol you are consuming. Hard liquor has calories left over from the carbohydrates that are fermented to create the ethanol. Some common drinks in shot portion sizes -
Scotch - 64 Cal
Rum - 66 Cal
Tequila - 65 Cal
Vodka - 65 Cal
Typically any alcohol above 80 proof(40% alcohol)has about 65 calories per serving. Where the serving size is consider to be 1 ounce. However some liqueurs can have closer to 200 calories per serving.
This depends entirely on what kind of hard alcohol it is, what brand it is, and what flavor it is. Any "nutritional" information should be clearly listed on the label.