Someone told me that "etc." is not formal. However, based on my research in internet, some people said that it is acceptable to use "etc." in academic paper.
How about IELTS writing exam then? Is "etc." acceptable in there?
English Language Learners Stack Exchange is a question and answer site for speakers of other languages learning English. It only takes a minute to sign up.Sign up to join this community
It isn't a question of formality, but one of clear writing
The use of "etc" tends to suggest that the student can't think of any more examples. Using "etc" assumes that the reader will know the rest of the list and this is often not the case. It is nearly always better to list fully, or rephrase.
In summer I visited Tokyo, Osaka etc.
Because I don't know how to complete the list, instead:
I summer I visited Tokyo, Osaka and many other cities in Japan.
There are situations when it can be used, for example in an infinite list:
The triangle numbers (1, 3, 6, 10, etc.) have been known since ancient times.
Take a look at https://english.stackexchange.com/questions/66149/is-it-suitable-to-use-etc-in-an-academic-paper on our sister site.