To prove his point, Sueco fills a tall size Starbucks cup with coffee, and then claims to pour the exact same contents into a grande cup, which is the company's version of a medium.
Not only does the coffee indeed fill the grande, it ~overflows~ from the cup.
Sueco isn't the first to surface this claim. In 2019, a Facebook page called Weekend Go Where Singapore also compared Starbucks cups in a video and showed a tall size nearly filling a grande to its brim.
About 16 million people have seen the musician's video, and while the evidence may appear damning, I couldn't help but be a little skeptical. Starbucks has been around since the '70s. If they've been scamming us on cup sizes this whole time, I wondered if it would have taken so many years for outrage to ensue.
And I wasn't alone! While some commenters suggested that Sueco's experiment makes sense because the smaller cup appears wider, so that would allow it to hold the same amount as a narrow cup that's taller...
...others wanted to see if he put anything inside the bottom of the cups to take up room before he started pouring:
So, I drove up to my local Starbucks and asked the incredibly patient barista for an empty cup of each size.
To start my personal experiment, I filled a short size cup with water and dumped that into the tall.
Though I did spill the tiniest amount, it was clear that the amount of coffee held by a short was nowhere near the amount that could satiate someone who regularly buys a tall.
To be fair, though, Sueco did not have a short in his video. He only compared the tall, grande, and venti sizes. So, I filled the tall cup with water and tried again, pouring the contents into the grande.
This time, I didn't spill any (nice!) and the cup still wasn't full. It was at this point that Sueco claimed his grande was overflowing from coffee that filled the tall, but unless coffee can multiply itself, that doesn't appear to be true.
At this point, I realized the video was BS. But to finish out a thorough investigation, I filled the grande cup and poured the water into my venti.
Spoiler Alert: The cup didn't fill.
According to Reader's Digest, the Starbucks cups hold the following ounces:
Short: 8 oz.
Tall: 12 oz.
Grande: 16 oz.
Venti: 20 oz.