GMAC has not published difficulty levels for any of the OGs up to OG 2018. Prep companies can only take our best guesses at the difficulty levels, based on the performances of our students.

Manhattan Prep has a tool called Navigator that allows students to record their answers to every OG question. Based on data from hundreds of thousands of students, we can judge the general difficulty level on each question: https://www.manhattanprep.com/gmat/stor ... navigator/
(Keep in mind, of course, that when students answer questions while studying, they are not doing these under test-like conditions. E.g. they may be taking extra time, hitting pause, or redoing questions. That said, we believe that it's a pretty good proxy for the difficulty level of real problems).

The new OG 2019 now has problems listed by difficulty level: https://www.mba.com/exam-prep/gmat-official-guide-2019
If you're very curious about difficulty, you could purchase this. But if you already own OG 2018, I wouldn't worry about buying a new book. Only 15% of the questions are new from one edition to the next, and specific difficulty ranking shouldn't impact your studies too much. After all, you'll never know the exact difficulty level of the questions you see while you're taking the real exam!

Hi estebanmorillo,

There is no true way to know the exact difficulty level of the OG questions. Are you using any other resources for your prep, or just the OG? What is your GMAT score goal?

You may find it helpful to read this article about
how to score a 700+ on the GMAT .

Feel free to reach out with further questions.

Good luck!