Where are you getting it from? I work at Starbucks, so it goes like this:
1) Milk
2) Espresso
3) Syrup
The milk has however many calories are on the side of your milk jug (not near me...sorry). They use whole milk unless you ask for 2% or nonfat. Espresso has nothing in it. The syrup is 10 calories per pump. The grande size has 4 pumps, so 40 calories, all sugar.
If you're getting it from 7-11 out of the push-button thing, then it has a bajillion calories (new number). But holy crap they're so friggin good!