Is a 187 on the PSAT a good score for a freshman and what percentile am I in?

Check your score report, it should have your percentile on it. I think 187 is equivalent to a score of 1870 on the SAT, and I believe that is a good score for anyone in high school, but if you wanted to get into the National Merit thing, you'd need higher. I think it's good because my score is less, but even then it's still a good, especially for a freshman. The most you can get is 2200. 1870/2200=85% so maybe your percentile is 85%.