Here is the link for the Korean class level test:
This is provided by King Sejong Institute, and before you take the test, you should sign up first.
There are two types of tests: beginner and intermediate. So select one depending on your Korean level.
Note that once you take a test, you can't take the same level test again for three months.
However, you can take a different level test.
Below is the recommended class according to test results.