Hello Lucky,

SAT exam is conducted by the College Board to test the candidate's knowledge of reading, writing and quantitative aptitude along with certain subjects. The exam is conducted for candidates who are interested in studying in universities in USA and some other countries. SAT tests are of two types - SAT Reasoning Test and SAT Subject Test. 

As for your question, there is no age limit as such but it has to be given by students who are appearing in class 12th so the general age of candidates is around 17 or 18.

For more information, follow the below link:

Https://studyabroad.careers360.com/articles/sat