Student Loan Calculator
See your monthly payment, total interest, and payoff date on any repayment timeline — and what extra payments do to both.
The repayment formula
Balance $35,000 at 6.5% on the 10-year Standard plan:
Payment: $397/mo · total interest: ≈ $12,700 · total repaid: ≈ $47,700
Adding $100/mo extra pays it off in about 7.7 years and saves roughly $3,300 of interest.
Term length vs. total cost ($35,000 at 6.5%)
| Plan length | Monthly payment | Total interest |
|---|---|---|
| 5 years | $685 | $6,100 |
| 10 years | $397 | $12,700 |
| 15 years | $305 | $19,900 |
| 20 years | $261 | $27,600 |
| 25 years | $236 | $35,900 |
On the 25-year timeline, interest exceeds the original balance. Longer terms are sometimes necessary for cash flow — but treat them as a floor, not a plan, and send extras when you can.
Federal borrowers: know your options first
Before optimizing payoff speed, check what your federal loans qualify for: income-driven repayment (payments tied to income), Public Service Loan Forgiveness if you work in government or nonprofits, and deferment protections. Aggressively prepaying a loan that would have been forgiven is money lost. Private loans have none of these safety nets — they're usually the right target for extra payments, highest rate first (see the debt payoff calculator for ordering multiple loans). Refinancing federal loans into private ones trades those protections for a lower rate — do that math carefully.
Same $35,000 balance at 6.5%, but instead of extra payments, imagine a 12-month forbearance with no payments made.
Unpaid interest accrues at roughly $35,000 × 6.5% ≈ $2,275 over the year. That interest typically capitalizes — gets folded into the principal — bringing the balance to about $37,275.
Restarting the standard 10-year plan on that larger balance raises the payment from $397/mo to about $423/mo, and total interest over the new 10-year clock from $12,700 to about $13,461 — on top of the $2,275 already accrued during the pause itself.
Common student loan mistakes
- Treating forbearance as free. As the example above shows, unpaid interest usually capitalizes at the end of the pause, permanently raising both the balance and every future payment — it postpones the bill, it doesn't erase it.
- Refinancing federal loans into private ones without weighing lost protections. Once refinanced, income-driven repayment, Public Service Loan Forgiveness eligibility, and deferment options are gone for good, even if the new private rate looks better on paper today.
- Choosing which loan to prepay by balance size instead of rate. Extra payments do the most good applied to the highest-rate loan first, regardless of which individual balance happens to be largest.
Frequently asked questions
What is the standard student loan repayment plan?
Fixed payments over 10 years — about $397/mo and $12,700 of interest on $35,000 at 6.5%.
Should I pay off student loans early or invest?
Prepay high-rate private loans first; low-rate federal loans with forgiveness potential often deserve minimum payments while you invest instead.
How does student loan interest work?
It accrues daily on principal; unpaid interest can capitalize after deferments, raising future interest.
Does a year of forbearance meaningfully increase what I owe?
Yes — on $35,000 at 6.5%, a 12-month forbearance accrues about $2,275 in interest that typically capitalizes, raising the balance to about $37,275 and the restarted payment to about $423/mo.
What happens to unpaid interest during deferment?
It usually capitalizes into the principal once the pause ends, unless it's a subsidized federal loan in deferment (not forbearance) — capitalized interest then itself starts accruing interest.
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Note: Models a fixed-rate amortized loan; income-driven federal plans compute payments differently. Not financial advice. Last reviewed: September 2026.