how many levels are there in duolingo?
25 but the levels are often misunderstood.
Your level is based on how many XP (experience points) you have earned. You could do the first lesson over and over and get to level 25 without learning anything, really. Or you could know a lot, test out of most of the skills, and finish the tree with a very low level. So although usually level 3 means a person is a beginner and level 18 means they are pretty advanced, it is not always true.