Student Loan Calculator: Payment & Total Interest

A student loan payment can look manageable each month while still producing a large interest cost over time. Estimating both figures from the same balance, rate and repayment term makes the trade-off between affordability and total repayment easier to see.

How to Use the Student Loan Payment Calculator

Enter the balance that will be repaid, the loan’s annual interest rate and a fixed repayment term. The model assumes equal monthly payments and a rate that does not change during repayment.

• Student loan balance: Principal balance used at the start of the repayment scenario.
• Annual interest rate: Stated fixed rate on the loan, not a guessed market average.
• Repayment term: Whole-number period from 1 through 30 years.

Separate calculations are more accurate when several loans have different interest rates or remaining terms. Combining balances under a simple average rate can distort the result because a larger loan should carry more weight than a smaller one.

Borrowers with federal loans should use the actual rate shown for each loan. Direct Loan rates depend on loan type and first-disbursement date, and the fixed rate assigned to a loan remains in place for its life.

How the Fixed Monthly Payment Is Calculated

Level-payment amortization spreads principal and interest across a fixed number of monthly payments. The formula uses the starting balance, monthly interest rate and total payment count.

P represents the starting balance, r is the annual rate divided by 12, and n is the number of monthly payments. A 0% interest scenario simply divides principal by the repayment months.

Using the default $35,000 balance, 6.5% rate and 10-year term, the estimated payment is about $397.42 per month. Total repayment is approximately $47,690.15, including about $12,690.15 of interest.

Longer terms generally reduce the required monthly amount because the balance is spread across more payments. More repayment time also gives interest longer to accumulate, so the lower payment can come with a substantially higher total cost.

Why an Actual Student Loan Bill Can Differ

Direct Loans from the federal program accrue interest daily rather than through a simple monthly interest convention. Payment dates, the exact number of days between payments and any unpaid accrued interest can therefore create small differences from a standard monthly amortization estimate.

Repayment-plan rules can create much larger differences. Current federal plans may use fixed, tiered, graduated or income-based payment structures depending on loan type, disbursement date and borrower eligibility, so a single fixed-term formula cannot reproduce every payment schedule.

Loans first disbursed on or after July 1, 2026 can be subject to newer federal repayment-plan rules, including Tiered Standard structures for certain Direct Loans. For plan eligibility, income-based estimates, forgiveness scenarios and current federal-plan comparisons, Federal Student Aid’s Loan Simulator is the appropriate tool.

Deferment, forbearance, capitalization, fees, variable private-loan rates and extra payments are also outside the model. Any of those features can change payoff timing or total interest.

Comparing Repayment Term and Total Interest

Monthly payment should be considered together with total interest rather than in isolation. Extending a loan can help near-term cash flow while increasing the amount paid for borrowing.

Shorter repayment usually has the opposite effect. A higher required payment retires principal faster, leaving less balance outstanding for future interest charges.

Extra payments can also reduce interest when they are applied to the loan balance according to the servicer’s rules. The calculator does not model a separate extra-payment schedule, so a payoff strategy with additional monthly amounts should be tested with a dedicated payoff tool or the federal Loan Simulator when applicable.

Refinancing requires a different decision framework from merely changing the term. A lower private refinance rate can reduce payment or interest, but refinancing federal debt into a private loan can give up federal repayment, deferment and forgiveness protections.