Model your student loan payoff under standard repayment vs accelerated extra-payment plan.
Payoff with extra payments
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Standard monthly payment
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New total payment
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Total interest (standard)
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Total interest (with extra)
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Your breakdown
Updates live as you type| Scenario | Payment | Payoff | Interest |
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Worked example
Take a $35,000 student loan balance at 6.5% on the standard 10 year plan, and suppose you add $200 a month on top of the required payment. The standard payment alone is about $397.42 a month, and on that schedule you would pay roughly $12,690 in interest over the full ten years. Paying $597.42 a month instead, the $200 extra goes straight against principal each month, so the balance falls faster and less interest accrues. The loan now clears in about 71 months, which is 5 years and 11 months, nearly 49 months ahead of the ten year schedule. Total interest drops to about $7,219, an interest saving of around $5,471. The lesson is that extra payments are most powerful early, when the balance and therefore the monthly interest charge are at their highest, so even a modest $200 a month meaningfully shortens the payoff.
How it is calculated
The standard payment comes from the level-payment amortization formula applied to your balance, rate, and term, the same math a servicer uses to set your minimum. The tool then simulates month by month with your higher total payment. Each month it charges interest equal to the balance times the monthly rate, applies the rest of your payment to principal, and reduces the balance, repeating until the balance reaches zero. Because principal falls faster when you pay extra, the monthly interest charge shrinks every month, which is why a fixed extra amount compounds into a large interest saving over the life of the loan. The comparison holds the interest rate constant, so it isolates the effect of paying more. It does not model forgiveness programs, income-driven plans, or variable rates, which follow different rules and can change the optimal strategy.