I just go to the MSAR and multiply the matriculation rate by 2. Except for obscenely prestigious schools, I've found that this generally gives a conservative acceptance rate. I think most schools accept 2:1 if not higher.
As above, the 2x class size is usually a good barometer for roughly how many students get accepted. However this is highly variable, and some schools (usually newer, or less competitive) will accept >3x class size (I know FAU accepts >270 for a class of 64). Some schools may also publish the number accepted online, like Wake Forest does.
Also, MSAR's GPA, MCAT, and other metrics are all based on accepted, not matriculated students.