Extra Payments on Student Loans
This calculator shows how much time and interest you save by adding extra money to your student loan payment each month or as a lump sum. Enter your balance, rate, minimum payment, and extra amount. On a $35,000 loan at 6.0%, an extra $150 per month cuts roughly three years off the term and saves thousands in interest.
Interest you never pay
Debt-free earlier — instead of .
- Same loan, two habitsAs you areWith extra
- Monthly payment
- Debt-free in
- Interest paid
- Total paid
That is a year of extra payments cutting off the interest bill.
At this payment the balance never clears — the payment is smaller than the interest accruing each month.
Tell your servicer in writing to apply extra money to the principal of your highest-rate loan, otherwise it is often treated as paying next month's bill early. Interest accrues daily at a day on the balance you entered.
Monthly vs Lump-Sum Extra Payments
A recurring monthly extra payment chips away at principal every billing cycle, which reduces the base on which daily interest accrues. The effect compounds: each month's interest charge is slightly smaller than the last, and a larger share of your next payment goes to principal. Over a 10-year term, even $50 per month extra on a $35,000 balance produces a noticeable shift in your amortization curve.
A lump-sum payment delivers a one-time principal reduction. It is most powerful early in the loan's life when the balance—and therefore daily interest—is highest. If you receive a tax refund, bonus, or gift and apply it as a lump sum, the calculator shows the resulting change in payoff date and total interest. You can also combine both: make a lump-sum payment now and add a modest monthly extra going forward. Run the tool twice—once with just the monthly extra, once with the lump sum added—to see the incremental benefit of each approach.
Where Your Extra Payment Goes
Extra payments should reduce principal, but not every servicer applies them that way automatically. Some servicers advance your due date instead, which means the money covers next month's payment (interest and principal combined) rather than going straight to principal. The result is no acceleration at all—you simply prepaid a future bill.
Contact your loan servicer to confirm that extra payments are applied to principal and that your due date is not advanced. Borrowers on student-loan forums report that a written request or an online account setting labeled "apply to principal" or "do not advance due date" is usually enough to fix this. Once you have confirmed the application method, track your balance monthly to verify the principal drops by the expected amount. For a multi-loan strategy that decides which loan gets the extra dollars first, see the avalanche-vs-snowball calculator or explore your overall payoff timeline.
Extra-payment examples are illustrative. Confirm with your servicer that payments are applied to principal and your due date is not advanced.
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Sources
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Sources: standard amortization formula (daily interest = principal × APR / 365.25); r/StudentLoans servicer-application discussions (2024-2026).
- Federal Direct Consolidation Loan interest rate — the weighted average of the loans being consolidated, rounded up to the nearest one-eighth of one percent (Federal Student Aid, studentaid.gov, Loan Consolidation).
- Amortisation, daily interest accrual and payoff arithmetic — standard loan mathematics; every figure on this page is computed from the numbers you enter.