A frappuccino is built on a sweetened base syrup that does two jobs: it sweetens the drink and it emulsifies the ice into that uniform texture. The base is mostly sugar syrup, which is why a grande coffee frappuccino starts around 230 calories before whipped cream, and flavoured versions like mocha or caramel reach 370–420.
The 'light' builds historically used a lighter base and skim milk to land nearer 200–250 calories for a grande. Even without an official light option, asking for skim milk and no whipped cream moves most frappuccinos down by 120–150 calories.
Key mental model: in a frappuccino, the base is a structural ingredient, not a topping — you cannot remove it entirely, only build around it with milk choice, size and the whip decision.