The same shots as a latte, more foam
A Starbucks Cappuccino is built from the same shot counts as its hot Caffè Latte: one shot (75 mg) in a Short or Tall, two shots (150 mg) in a Grande or Venti. The two drinks differ in the ratio of foam to steamed milk, not in caffeine; a cappuccino just tastes stronger because there’s less milk diluting each sip.
That also means, unusually among Starbucks sizes, a cappuccino doesn’t get any stronger between Grande and Venti: both carry 150 mg, the extra volume in the Venti going to foam rather than another shot.
Compared to home cappuccino
USDA’s generic figure for a home-style cappuccino, one shot with steamed milk in a smaller cup, runs close to a single Starbucks shot too. The main difference between chains and home brewing is cup size and shot strength, not the basic one-or-two-shot structure, and that holds whether the milk is steamed into a thick microfoam or a lighter one, since foam style changes texture, not caffeine.
That also means ordering “small” for the caffeine and “large” for the milk-to-foam ratio isn’t possible the way it is with a latte: past Grande, the drink just gets frothier, not stronger.
Where it fits in a day
At 150 mg, a Grande or Venti cappuccino sits under the 200 mg single dose EFSA assessed as safe for healthy adults. Two Grandes, 300 mg, leave 100 mg of the 400 mg daily figure the FDA cites for healthy adults. In pregnancy, where ACOG uses a 200 mg daily ceiling, a Short or Tall at 75 mg leaves the most room.