Wow, well the answer varies greatly depending on a person's LSAT and GPA.
Safety: a school for which your numbers fall in the top 25%
Target: a school for which your numbers fall in the middle 50%
Reach: a school for which your numbers fall in the bottom 25%
Of course, there are shades of gray in there as well. A low GPA can be overcome with an exceptional LSAT score. For example, Northwestern admits people with ~2.9 and 170+ LSAT score. But the above guidelines are the general rule of thumb.