Before you accelerate: the federal-loan checklist
Student loans are the one debt where faster isn't automatically better. If you're pursuing PSLF or on an income-driven plan headed for forgiveness, extra principal can be money donated to the servicer. If you're on the standard plan (or private loans) with no forgiveness path, the math is the ordinary amortization above and extras work beautifully — target the highest rate first (see snowball vs avalanche), keep the employer match and emergency fund ahead of acceleration, and confirm extras post as principal-only.
How this calculator works
Standard repayment amortizes exactly like any fixed loan, and extra payments follow the same principal math:
Monthly payment
M = P · r(1 + r)ⁿ ÷ ((1 + r)ⁿ − 1)
Extra payments
every extra dollar cuts the balance, so next month’s interest = smaller balance × r
- P — amount borrowed (principal)
- r — monthly interest rate — annual rate ÷ 12, as a decimal
- n — number of monthly payments (years × 12)
- M — the fixed monthly payment
This models fixed-payment plans — standard federal 10-year and most private loans. Income-driven federal plans follow different rules this calculator doesn’t model; for those it’s still useful as the cost of a fixed payoff plan to compare against.
Worked example
A $30,000 student loan at 5.5% on the standard 10-year plan, then with an extra $100/month.
| Standard payment (10 yr) | $325.58 |
|---|---|
| Interest, standard | $9,069 |
| Payoff time with +$100/mo | 7 yr 2 mo (86 months) |
| Interest saved | $2,753 |
| Time saved | 34 months |
On the standard plan the loan costs $9,069 in interest; adding $100 a month clears it nearly three years early and saves $2,753. This models fixed-payment repayment — standard federal and most private loans. One caution for federal borrowers: income-driven plans and forgiveness programs follow different rules, and paying extra can reduce a future forgiveness benefit, so confirm your plan before accelerating.
Frequently asked questions
How long will it take to pay off my student loans?
The federal standard plan is 120 months (10 years); your servicer sets the payment so the balance amortizes to zero. Enter your balance and rate above with a 120-month term to see the schedule — then add an extra amount to watch years disappear.
Do extra payments work on student loans?
Yes — federal and private student loans have no prepayment penalties. One caution: instruct your servicer to apply extras to the CURRENT loan’s principal, not as an early next payment ("pay ahead" status), and target the highest-rate loan in your group first.
Should I pay off student loans early or invest?
Compare the loan rate to expected after-tax returns. At 4–5% federal rates the case for investing (or just capturing an employer 401(k) match first) is strong; at 7–9% (grad/private), prepayment is a solid guaranteed return. Also weigh federal protections you give up by rushing: income-driven plans and potential forgiveness.
Does this calculator work for income-driven repayment (IDR)?
Not directly — IDR payments track your income, not amortization, and remaining balances may be forgiven after 20–25 years. This tool models fixed-payment plans (standard/private/refinanced). If you’re on IDR and aiming for forgiveness, extra payments may even be counterproductive; check your plan first.
Should I refinance student loans?
Private refinancing can cut the rate for strong credit — but refinancing FEDERAL loans forfeits IDR, deferment, and forgiveness permanently. Refinance private loans freely; refinance federal only if you’re certain you won’t need the safety net.
Which loan should I pay first with multiple student loans?
Highest rate first (avalanche) saves the most; smallest first (snowball) motivates. Run the comparison with your real loans in the debt snowball calculator.
Related calculators
- Loan Payoff Calculator — See how extra payments shorten your loan and how much interest you save.
- Debt Snowball Calculator — Compare the snowball and avalanche payoff methods side by side across all your debts.
- Personal Loan Calculator — Payment, total interest, and full schedule for any personal loan — plus early-payoff savings.
- Debt Consolidation Calculator — Your debts vs. a real loan offer at the same monthly budget — fees counted, longer-term tricks exposed.
Disclaimer: Educational purposes only — not financial advice. IDR/forgiveness rules change; verify with your servicer and studentaid.gov. See our Terms of Use.