How this calculator works
Same month-by-month amortization as credit cards: interest accrues on the remaining balance, extra payments go entirely to principal and compound your savings.
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Student Loan Payoff Calculator — Extra Payment Savings
Federal and private student loans amortize monthly just like mortgages. Enter the balance, rate and monthly payment to see the payoff date — then test extra payments.
Scenario examples (2026 rates)
| Loan balance ($) | Debt-free in | Total interest paid |
|---|---|---|
| 15,000 | 4 yr 3 mo | $2,172.72 |
| 22,500 | 6 yr 10 mo | $5,395.27 |
| 30,000 | 10 yr 0 mo | $10,811.63 |
| 45,000 | 19 yr 3 mo | $33,965.5 |
| 60,000 | 46 yr 4 mo | $130,029.27 |
Every number above is computed by the same in-browser engine as the calculator — nothing is hardcoded.
Federal versus private loans in payoff planning
The amortization math is identical, but the surrounding rules are not, and those rules decide your strategy. Federal loans carry fixed rates set by Congress, offer income-driven plans that can drop payments to zero, allow deferment and forbearance without default, discharge on death or total disability, and feed Public Service Loan Forgiveness after 120 qualifying payments. Private loans price by credit, sometimes variable, and offer few protections if income stops, though most provide short forbearance. When you plan payoff, federal borrowers should first answer whether forgiveness applies to their career; if it does, extra payments destroy value. Private borrowers have no such option, so the entire question is rate versus expected investment return. One more asymmetry: federal servicers apply extra payments to the highest-rate loan or per your standing instruction, while private servicers vary, so check how each of your loans handles prepayment before automating anything.
Choosing which loan to attack first
With multiple loans, three orderings compete. Rate-first, avalanche, minimizes total interest and is the correct default: a 7.5 percent unsubsidized loan should absorb every extra dollar before a 4.9 percent subsidized one. Balance-first, snowball, closes loans faster and works when motivation is the binding constraint. A third ordering is specific to student debt: attack subsidized versus unsubsidized deliberately, because subsidized loans stop accruing during deferments and forbearances while unsubsidized ones silently grow, making unsubsidized balances more dangerous per dollar of rate. Federal consolidation simplifies payments into one weighted-average rate but rounds up to the nearest eighth of a percent and resets some forgiveness clocks, so it is rarely an optimization. List every loan with its rate, type and balance, sort by rate descending for the math, and only deviate to snowball when you have honestly concluded that finishing small loans is what keeps you in the fight.
Extra payments and where the money actually goes
Servicers are notorious for misapplying extra payments by advancing the due date instead of reducing principal, which pauses the loan without saving a cent of interest. Protect yourself: submit a standing instruction, in writing through the servicer portal, that overpayments go to principal, and specify highest-rate loan first if you hold several. Verify on the next statement that the principal balance fell by the full extra amount. Interest accrues daily on federal loans using a simple daily factor, balance times rate divided by 365, so paying a few days after the due date adds a small interest charge that the next payment absorbs. Timing extras right after the payment posts, rather than at month end, keeps more of each dollar on principal. When a windfall arrives, a tax refund or bonus, applying it as a lump to principal beats spreading it across months, because every day the principal is lower is a day it earns no interest.
FAQ
Should I pay extra or invest?
Compare your loan rate to expected investment returns. Above ~6% APR, paying down the loan is usually the better risk-free return; below 4%, investing often wins.
Does refinancing help?
If you qualify for a rate 1.5%+ lower on private loans, yes. Refinancing federal loans forfeits income-driven plans and forgiveness — usually a bad trade.
Extra $100/month — how much does it save?
On a $30,000 loan at 6.5% with the standard $342 payment, an extra $100/month saves about 1.5 years and $3,000+ in interest.
How do federal grace periods and interest capitalization change the balance?
Direct subsidized loans accrue no interest while you are in school at least half time and during the six-month grace period. Unsubsidized loans accrue from disbursement, and that unpaid interest capitalizes, is added to principal, at the end of grace or after periods like deferment. On $30,000 of unsubsidized loans at 6.5 percent, four years of school plus grace adds roughly $7,600 of accrued interest, and if it capitalizes you start repayment owing about $37,600 with interest then charging on interest. Private loans capitalize on their own schedules, often annually or at repayment start. The practical move: pay the accruing interest monthly while in school or during grace, which on the example above costs about $160 per month but prevents thousands of dollars of capitalized balance. Enter your post-capitalization balance in this calculator, not the original principal.
Does the SAVE plan or PSLF change what I should pay?
If you are pursuing Public Service Loan Forgiveness, extra payments are wasted money: only the 120 qualifying monthly payments under an income-driven plan count, and paying more than that amount earns nothing. Enroll in an IDR plan, pay exactly the billed amount, and track qualifying employment annually. For SAVE-style plans more broadly, if your income-based payment is below monthly accrual, the unpaid interest is not capitalized while you remain enrolled, but the balance also never shrinks, so forgiveness timelines matter more than payoff speed. The decision rule: pursuing forgiveness, pay the minimum and invest the difference; not pursuing it, model payoff here and target any extra at your highest-rate loan. If you refinance federal loans into private ones to chase a lower rate, you permanently forfeit IDR, PSLF and deferment protections.
Should I refinance student loans in 2026?
Refinancing makes sense in three cases: private loans at least 1.5 to 2 points above current offers, federal loans you have decided never to use for IDR or forgiveness, and a stable income with a credit score around 700 or better plus optionally a cosigner release path. Current private refi rates for well-qualified borrowers run roughly 4.5 to 8 percent fixed, so a borrower holding 7 to 8 percent federal paper from the 2023-2024 origination era can save meaningfully. On $40,000 over ten years, dropping from 7.5 to 5.5 percent cuts the payment by about $40 per month and total interest by about $4,700. Do not extend the term to lower the payment unless cash flow demands it; a 20-year refi can cost more total interest than the original 10-year federal loan at a higher rate.