<p>how do you?</p>
<p>One man's opinion, and geared toward more selective schools. Obviously, not an exact science, but if you mean simply chances of admission (and not appropriateness or desirability of the instituition), a "quick and dirty" simple test would be that if you are in the top 25% of entering class on both standardized tests and GPA, you might classify it as a match. If you fall below the top 25%, but within the mid-50%, it can be a reach. Of course, one's own other credential matter greatly. Athletes and URM's and musical geniuses (where those things matter) match below these ranges. Conversely, those with just the gpa and scores without outstanding other credentials often face admissions uncertainty at highly competitive schools and can not be comfortable they "match" even at the highest end. Some schools, HYPS, perhaps must always be considered a reach absent extraordinary other talents or unusual situation that provides an independent basis for admission.</p>
<p>To the top 25% statistic, I'd add one more: admissions rate. Even if you're well above the 25% mark, if a school has an admissions rate of 20%, it's a reach.</p>