Starbucks has a secret size called the Trenta but it's only available for cold drinks and you must ask for it.
The secret size at Starbucks is the Trenta size which is 31 ounces.
The 31 ounce Trenta sized drink is the largest size that Starbucks has.
The Trenta Starbucks 31 ounce cup is a super sized cup that is perfect for days when you need a pick me up but it's only available for certain cold beverages.
A trenta is one of the two off-menu Starbucks drink sizes that are not openly advertised, but can be ordered whenever you like.
Starbucks may not list this gargantuan drink size alongside its other size options, but they don't try to keep it a secret, either.
You can only order a trenta for cold drinks, specifically iced teas, iced coffee, cold brew, and Refreshers.
Starbucks reportedly used to sell trenta Frappuccinos, but no longer does - probably because 31 ounces of the sweet drinks would be probably be pretty irresponsible.