Find your PSAT score on the bottom axis and then follow that line up to your ACT score. If you’re in the pink ACT zone, you should focus on the ACT. If you’re in the green SAT zone, you should consider focusing on the new SAT. Many students will find that they fall into the Decision Zone. 

Some factors to consider if you’re in the Decision Zone:

• Is your ACT Science score significantly lower than your other three section scores? If so, your ACT composite score may be artificially low since most students improve once they understand how to approach the Science section.
• Have you spent time working on SAT-style questions in school or have you spent time prepping for either test? If so, consider that you can improve your other score as well.
• Was the vocabulary on the PSAT a stumbling block? If so, consider that improvement in grammar skills, math skills, and test-taking skills can be accomplished much faster than vocabulary improvement (although your vocabulary can definitely be improved!).
• Do you have extra time or other accommodations for one test but not the other? If so, you will likely be more successful on that test.
• Do you have any significant schedule considerations around any of the test dates, like finals or major extracurricular activities?

The College Board and ACT, Inc. have jointly released a Concordance Table which can help decide which test is better for you if you have an SAT score and an ACT score. Click here for that table.