Student Loan Repayment Calculator
Enter your loan amount, interest rate, and repayment term to see your monthly payment, total interest, and year-by-year amortization breakdown.
Student loan amortization works the same as any installment loan: each monthly payment covers the interest that accrued since the last payment, and whatever remains reduces the principal. Because interest accrues on the current balance, early payments are heavily weighted toward interest. As the balance falls, an increasing share of each payment reduces principal — a pattern that continues until the balance reaches zero at the end of the term.
Federal and private student loans differ in more than interest rates. Federal Direct loans carry fixed rates set by Congress each year (6.53% for undergraduate borrowers in 2024–25), income-driven repayment options, and forgiveness programs like PSLF. Private loans offer potentially lower rates for well-qualified borrowers but lack these safety nets. The loan type you select in the calculator affects the tips displayed but does not change the underlying math.
Paying extra principal early in the loan term has a disproportionate impact on total interest paid. Because interest compounds on the remaining balance, reducing the balance sooner eliminates interest that would have compounded over years. Even one extra payment per year — applied entirely to principal — typically cuts one to three years off a 10-year loan and saves several thousand dollars in interest.
Popular Scenarios
- $30,000 Student Loan at 5% for 10 Years
- $50,000 Student Loan at 6.5% for 10 Years
- $100,000 Student Loan at 7% for 20 Years
- $20,000 Student Loan at 4.5% for 10 Years
- $40,000 Student Loan at 5.5% for 10 Years
- $75,000 Student Loan at 7% for 25 Years
- $150,000 Student Loan at 7.5% for 25 Years
- $60,000 Student Loan at 6% for 15 Years
- $50,000 Student Loan at 6.5% for 20 Years
- $25,000 Student Loan at 5% for 10 Years
- $80,000 Student Loan at 6.5% for 20 Years
- $200,000 Student Loan at 8% for 25 Years
- $35,000 Student Loan at 4% for 10 Years
- $120,000 Student Loan at 7% for 20 Years
- $45,000 Student Loan at 5.5% for 15 Years
How is the monthly student loan payment calculated?
The standard formula is M = P × [r(1+r)^n] / [(1+r)^n − 1], where P is the loan amount, r is the monthly interest rate (annual rate ÷ 12 ÷ 100), and n is the total number of monthly payments. This produces a fixed payment that fully amortizes the loan over the chosen term.
What is the difference between federal and private student loans?
Federal loans have Congress-set fixed rates, income-driven repayment plans, forbearance options, and forgiveness programs (PSLF, IDR forgiveness). Private loans are issued by banks and credit unions at market rates — potentially lower for borrowers with excellent credit — but offer no federal repayment protections. Refinancing federal loans into private loans permanently removes access to federal programs.
Does paying extra every month really make a big difference?
Yes. On a $30,000 loan at 5% for 10 years, paying an extra $50/month saves approximately $1,100 in interest and shortens the term by over a year. The savings grow with higher balances and rates. Any extra payment should be directed to principal — confirm with your servicer that it is not being applied to future payments.