How to Use This Student Loan Calculator
This calculator estimates your monthly payment, total interest, and total repayment cost for a student loan based on your balance, interest rate, and repayment term. It uses the standard fixed-rate amortization formula, which applies well to the Standard Repayment Plan for federal loans and to most private student loans, though federal borrowers have several other repayment options that work quite differently, covered below.
The Standard Repayment Plan
The federal Standard Repayment Plan spreads payments evenly over 10 years (or up to 30 years for consolidation loans), with a fixed monthly payment calculated the same way this calculator works: using your balance, interest rate, and term in the standard amortization formula. This plan typically results in the lowest total interest paid among federal repayment options, since it pays off the loan fastest, but it also has the highest monthly payment relative to income-based alternatives.
Income-Driven Repayment Plans Work Differently
Federal student loan borrowers can also choose income-driven repayment (IDR) plans, which calculate your monthly payment as a percentage of your discretionary income rather than using the standard amortization formula this calculator applies. Under IDR plans, your payment can be lower than what this calculator estimates — sometimes dramatically so for lower-income borrowers — but the repayment period is extended, often to 20 or 25 years, and any remaining balance may be forgiven at the end of the term (though forgiven amounts can potentially be treated as taxable income under current law, depending on the program). Because IDR payments are based on income rather than balance and rate alone, this calculator's output should be treated as an estimate of standard repayment, not IDR repayment. See our guide on income-driven repayment plans for a full comparison of available plans.
Federal vs. Private Student Loans
Federal and private student loans differ significantly in structure, protections, and repayment flexibility. Federal loans offer fixed rates set by Congress each year, a range of income-driven repayment options, deferment and forbearance protections, and potential eligibility for forgiveness programs. Private student loans, issued by banks, credit unions, and online lenders, may offer fixed or variable rates based on your (or a co-signer's) creditworthiness, and generally have far fewer built-in protections and repayment flexibility. Our guide on federal vs. private student loans explains the key differences to weigh before borrowing or choosing where to focus extra payments.
Should You Refinance Your Student Loans?
Refinancing combines one or more student loans into a new loan, often with a private lender, potentially at a lower interest rate if your credit and income have improved since you originally borrowed. However, refinancing federal loans with a private lender means permanently giving up federal protections like income-driven repayment eligibility and potential forgiveness programs. Our guide on student loan refinancing walks through the tradeoffs and when refinancing tends to make the most sense.
How Interest Accrual Works
Depending on the loan type, interest may begin accruing immediately upon disbursement (unsubsidized federal loans and most private loans) or may be paid by the government while you're in school and during grace periods (subsidized federal loans, for borrowers who qualify based on financial need). If interest accrues while you're not making payments — during school, a grace period, deferment, or forbearance — that unpaid interest can be added to your principal balance (capitalized) at certain trigger points, increasing the balance on which future interest is calculated. This calculator assumes a static starting balance and doesn't model in-school accrual or capitalization, so if you're estimating payments before you've finished borrowing, keep in mind your eventual balance may be higher than your current balance.
Choosing the Right Repayment Strategy
The right repayment plan depends on your income stability, career field, and whether you're pursuing a forgiveness program. Borrowers with high, stable income and a goal of minimizing total interest often benefit from the Standard Plan or an even more aggressive extra-payment strategy. Borrowers with lower or variable income, or those pursuing Public Service Loan Forgiveness, often benefit more from an income-driven plan despite the longer timeline. Our guide on choosing the right student loan repayment plan walks through the decision factors in more depth.
Extra Payments and Interest Savings
Because student loans use the same amortization principles as other installment loans, any extra payment you make goes directly toward reducing your principal balance (assuming you specify that it should be applied to principal, not a future payment), which reduces the interest that accrues in every subsequent month. Even modest extra payments made early, when the balance and accruing interest are largest, can meaningfully shorten your repayment timeline and total interest cost.
Limitations of This Calculator
This tool models a fixed-rate, fully amortizing loan under the Standard Repayment structure. It does not calculate income-driven repayment amounts, capitalized interest, loan forgiveness scenarios, or variable interest rates found on some private loans. For federal loan borrowers, the official numbers on StudentAid.gov or your loan servicer's website will reflect your actual plan and balance far more precisely than this general-purpose estimator. Use this calculator for planning and comparison purposes only, not as a substitute for information from your loan servicer.