Private student loans tend to cost more than the education loans offered by the federal government, but are less expensive than credit card debt. The federal education loans offer fixed interest rates that are lower than the variable rates offered by most private student loans. Federal education loans also offer better repayment and forgiveness options. Since federal education loans are less expensive than and offer better terms than private student loans, you should exhaust your eligibility for federal student loans before resorting to private student loans.

Private student loans typically have variable interest rates, with the interest rate pegged to an index, such as LIBOR or PRIME, plus a margin. The LIBOR index is the London Interbank Offered Rate and represents what it costs a lender to borrow money. The Prime Lending Rate is the interest rate lenders offer to their most creditworthy customers. A rate of LIBOR + 2.8% is roughly the same as PRIME + 0.0%. The spread between LIBOR and PRIME has been growing over time. So all else being equal, it is better to have an interest rate pegged to the LIBOR index, as such a rate will increase more slowly than a rate pegged to the PRIME index.

The interest rates and fees you pay on a private student loan are based on your credit score and the credit score of your cosigner, if any. Generally, if your credit score is less than 650 (FICO), you are unlikely to be approved for a private student loan. An increase of just 30 to 50 points in your credit score is often enough to get you better terms on your loan.