What your student loan really costs
Federal student loans default to the Standard Repayment Plan: a fixed monthly payment that clears the balance in 10 years. The payment uses the ordinary amortization formula, so a $30,000 balance at the 2024–25 undergraduate rate of 6.53% costs $341.10 a month and about $10,932 in interest over the decade — total repaid, roughly $40,932. Private loans and refinanced loans follow the same math with whatever rate and term you were offered.
Longer terms lower the payment but raise the cost. Stretching that same loan to 20 years drops the payment to $224.20 but more than doubles the interest to $23,809. The calculator shows both figures side by side so the trade-off is explicit, and the year-by-year table shows how slowly the balance moves in the early years of a long term.
Extra payments are the cheapest way to cut the total. Because there is no prepayment penalty on federal or almost any private student loan, every extra dollar reduces principal immediately. Adding $100 a month to the example loan pays it off 2 years 10 months early and saves about $3,365. Enter an extra amount to see the exact saving and the new payoff date.
Unsubsidized loans accrue interest while you study. If you are still in school or in the six-month grace period, enter the months until repayment starts. The calculator accrues simple interest for that time and capitalizes it — adds it to the principal — when payments begin, which is what happens on unsubsidized federal loans and most private ones. Subsidized federal loans do not accrue interest during those periods, so leave the field at 0 for them.