Updated · Built and checked by the PlinzoTools team, formulas tested against published sources
Calculate your student loan's monthly payment and total interest over its repayment term.
Total interest over the life of the loan: $12092.61
$434.11
Student loans use the same amortization formula as any fixed-rate installment loan, but are commonly modeled over much longer terms (10, 20, even 25 years for some repayment plans) than a typical personal or auto loan -- which meaningfully increases total interest paid relative to the original principal, a dynamic worth seeing clearly before committing to a repayment plan.
Enter your loan principal, interest rate, and repayment term in years.
Monthly Payment = P × r ÷ (1 − (1 + r)−n)
This is standard amortized-loan math -- it doesn't model income-driven repayment plans (which base payments on income rather than a fixed amortization schedule), deferment, forbearance, or loan forgiveness programs, all of which can substantially change actual payments and total cost for federal student loans specifically.
Use this to compare standard repayment plans at different terms, or to see how a longer term lowers the monthly payment but increases total interest paid. If you want to see the effect of paying extra each month, use the Loan Payoff Calculator instead.
Take the same hypothetical $40,000 balance at 5.5%. Over 10 years the payment is about $434 and total interest is about $12,080. Stretch it to 20 years and the payment falls to about $275, but total interest rises to roughly $26,000. You would pay about $159 less each month, but more than double the interest. Neither choice is universally right. It depends on whether monthly cash flow or total cost matters more during this stage of your life, and on whether your loan allows extra payments without penalty.
Students often have several loans with different rates, especially if they borrowed each year. The calculator handles one loan at a time. To estimate your combined picture, run each loan separately with its own balance, rate, and remaining term, then add the payments together. This also helps you see which loan carries the highest rate. Paying extra on the highest-rate loan first usually reduces total interest the most, and you can test the effect with the Loan Payoff Calculator.
Some loans accrue interest while you are in school or in deferment. If unpaid interest is added to the principal, called capitalization, your balance at repayment can be higher than the amount you originally borrowed. Use the current balance shown by your servicer at the time repayment begins, not the original amount. The calculator has no way to know about capitalization or grace periods, so it depends on you entering the correct starting balance.
Federal student loan programs change over time, including repayment plan options, forgiveness rules, and interest treatment. For official figures and current rules, check the Federal Student Aid website (studentaid.gov) or your loan servicer directly. For private loans, your lender's promissory note and monthly statement are the definitive source. If you are weighing refinancing or consolidation, be aware that moving federal loans into a private loan can mean losing federal protections, so consider that carefully or speak with a qualified financial advisor.
More months means more time for interest to accrue on the outstanding balance, even though the monthly payment itself is lower -- the tradeoff is lower monthly cash flow burden versus higher total lifetime cost.
No -- income-driven plans base your payment on your income rather than a fixed amortization schedule, which this calculator doesn't simulate; check your specific loan servicer for an income-driven repayment estimate.
Yes. Fixed-rate private loans use the same amortization math. For variable-rate loans the result is only an estimate at the current rate, since the payment can change.
Generally yes, because extra money reduces principal sooner and lowers future interest. Confirm with your servicer how extra payments are applied and whether they can be directed to principal.
It is a close estimate for a fixed-rate loan. Your servicer's figure can differ due to rounding, payment dates, and any accrued interest.
Reference: Consumer Financial Protection Bureau