Barcelona is bilingual. The Spanish spoken here sounds nothing like Mexico City, and Catalan is everywhere. This is what you actually need to navigate daily life in BCN.
Duolingo is great at what it does. What it does isn't teach you the Spanish you need to actually live in CDMX. Here's the structural problem, and what works instead.
The taco stand is a social ritual with unspoken rules. Here's what to say, how to say it, and what never to do at a CDMX taquería counter.
The honest answer: less than you think to survive, more than most apps give you to actually connect. Here's what level you need for what kind of life in CDMX.
Same language, very different experience. If you learned Spanish from a Spain based app or textbook, here is what changes when you land in Mexico.
Forget textbook Spanish. Here are 50+ real phrases you will hear on the streets of Mexico City, including words that will get you in trouble if you use them wrong.