Student Loan Calculator

About This Tool

The Student Loan Calculator uses the standard amortization formula to compute your monthly payment, total cost of the loan, total interest paid, and exact payoff date. It generates a complete month-by-month amortization schedule showing exactly how each payment is split between reducing your principal balance and paying interest charges. Whether you are planning for repayment after graduation, evaluating refinancing options, or deciding between repayment terms, this tool gives you the numbers you need to make an informed decision.

How the Amortization Formula Works

The calculator uses the standard fixed-payment amortization formula: PMT = P[r(1+r)^n] / [(1+r)^n - 1], where P is the loan principal (your balance), r is the monthly interest rate (annual rate divided by 12), and n is the total number of monthly payments (years times 12). This formula determines the fixed monthly payment that fully repays the loan over the specified term. In the early months, a larger portion of each payment goes toward interest because the balance is highest. As you pay down the principal, the interest portion shrinks and more of each payment goes toward the balance. By the final months, nearly your entire payment reduces the principal. This shift is clearly visible in the amortization schedule this tool provides.

Federal Student Loan Interest Rates in 2026

Federal student loan interest rates are set annually by Congress based on the 10-year Treasury note yield. For the 2025-2026 academic year, rates are approximately 5.50% for undergraduate Direct Loans, 7.05% for graduate Direct Loans, and 8.05% for PLUS Loans (parent or graduate). Private student loan rates vary widely depending on your credit score and lender, ranging from 4% to 14%. The rate you enter in this calculator should match the rate on your specific loan, which you can find on your loan servicer website or in your loan documents. If you have multiple loans at different rates, you can calculate each separately or use the weighted average rate.

Standard vs Extended vs Income-Driven Repayment

The standard repayment plan for federal student loans is 10 years with fixed monthly payments, which is what this calculator models by default. Extended repayment stretches the term to up to 25 years, lowering monthly payments but dramatically increasing total interest. For a $35,000 loan at 5.5%, the standard plan costs $380/month with $10,580 in interest. Extending to 25 years drops the payment to $215/month but the total interest balloons to $29,400 — nearly three times as much. Income-driven plans (IBR, PAYE, SAVE) set payments at 10-20% of discretionary income and forgive any remaining balance after 20-25 years, but these plans are not modeled by standard amortization since payments change with income.

The Impact of Extra Payments

Making extra payments toward your student loan principal is one of the most effective ways to reduce total interest and shorten your repayment timeline. Even small additional payments compound over time. Adding just $50 per month to the standard payment on a $35,000 loan at 5.5% saves approximately $2,100 in interest and pays off the loan 18 months early. Adding $100 extra per month saves about $3,600 and shaves nearly 3 years off the timeline. When making extra payments, always confirm with your servicer that the additional amount is applied to principal, not future payments. Some servicers advance your due date instead of reducing principal unless you specifically request otherwise.

When to Consider Refinancing

Refinancing replaces one or more existing loans with a new loan at a different rate and term. It makes financial sense when you can get a meaningfully lower interest rate (typically 1% or more below your current rate), when you have stable income and good credit (700+), and when you do not need federal protections like income-driven repayment or Public Service Loan Forgiveness. Refinancing federal loans into a private loan permanently removes federal benefits, so weigh the interest savings against the loss of safety nets. Use this calculator to compare your current loan terms with the proposed refinanced terms to see the total interest difference. A rate reduction from 6.5% to 4.5% on a $40,000 loan over 10 years saves approximately $4,700 in total interest.

Student Loan Forgiveness Programs

Several federal programs offer student loan forgiveness after a qualifying period. Public Service Loan Forgiveness (PSLF) forgives the remaining balance after 120 qualifying payments (10 years) while working full-time for a government or nonprofit employer. Teacher Loan Forgiveness offers up to $17,500 for teachers in low-income schools after 5 years. Income-driven repayment plan forgiveness occurs after 20-25 years of qualifying payments, though the forgiven amount may be taxable as income. If you qualify for any forgiveness program, this changes the calculus significantly: you may want to minimize monthly payments and maximize the forgiven amount rather than paying off the loan as fast as possible. This calculator shows the standard repayment path, which is the right comparison baseline whether or not you pursue forgiveness.