According to Lux, student loan expert, the main borrowing metric students should focus on is the total amount of student loan debt they'll have after college. With that in mind, the ideal limit for student loan debt varies from person to person based on various factors: the industry they plan to enter, their first-year earnings, and the earning power they will likely have as they progress through their careers. That said, Lux suggests borrowing up to a person's expected salary after graduation as a general rule of thumb. This basic limit will prevent most students from borrowing more than they can reasonably repay while letting those who will likely earn more after college borrow more so they can graduate. Lux gives the following example:"If you expect to earn $65,000 per year after school, you want to limit borrowing to $65,000."