mango clothes start at a US small and a European XS
they run fairly true to size
actually its the opposite. the US XSmall = EU Small (because American people are generally bigger on average)
depending on which tag you read, the sizing varies.
if you're going by true misses sizing, they run close to TTS a tiny bit on the small side maybe. but compared to most chain brands they run small to very small (although the looser-styled tops tend to be very loose, even in the smallest sizes)
ex, I wear a 24/25 in premium denim, J Crew's 0 is huge on me, Mango's 2 is often (not always) too small.
the b&m stores will only carry sizes US XS-L in tops, and 2-14 in bottoms, but more sizes are available online.
personally, I'm not a fan of Mango. I can find way better quality at the same price. I bought very little from them even with my employee discount when I worked at the Bellevue, WA store, and its US franchise system is very badly managed.
also the website doesn't really list fabric content, so be aware that they use a lot of synthetic fibers.
I find them to be on the small (very) small size, compaired to other european stores (H&M, Zara...)
I find them to run really really small compared to British sizes! I find American sizes, with the exception of Abercrombie - run big compared to British sizing. So if you are going by American sizing then Mango is going to be titchy tiny in comparison!
^well American and British sizing are not supposed to be the same/interchangeable. It's not a matter of one running bigger than the other; the respective sizing systems are designed to start and end at different numbers. I would never wear the same size in American and British sizes, there are charts out there that tell you what size you should wear in different sizing systems.
And Abercrombie is small because it's more of a Junior store.