How Important is the GRE General / Subject compared to ACT / SAT? I am about to graduate with a B.A. in Math and want to pursue a Ph.D. in the subject. I understand that most graduate schools require both the general GRE as well as the subject math test.

I am wondering exactly how important these exams are for admissions. Obviously it varies by school, so I was hoping people could compare them to undergraduate admissions with the ACT or SAT.

For example, as a high school student we were told that SAT / ACT scores were an important but not determining factor in admissions. Accordingly, I stressed quite a bit about my scores and even retook the ACT.

For a graduate program, especially in mathematics, is the general GRE really that important? Or is it more of a check mark — that is, to make sure candidates are able to read and write, but not necessarily to pick those with the highest scores.

Similarly, are the subject tests decisive at all? Or are they used to just make sure that you know the "basics," while the course load and letters of recommendation are far more important.
Certain programs in Mathematics will heavily weight the GRE Subject test for mathematics programs. Many top programs will have a threshold that they expect students to pass for them to actually read the application. Usually, one should view the subject test more as something that can help you be considered, not something that can get you accepted to a program.

This being said, it is definitely something that should not be considered just as a formality when applying to top 25 universities.