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Student Loan Extra Payments Calculator

This calculator estimates how making extra payments affects the payoff date and total interest on a student loan. It supports regular monthly extra payments, a biweekly payment cadence (every two weeks), and one-time principal reductions.

Results are estimates using standard amortization math. Use the scenario that matches how you will actually send extra money: add to each monthly payment, add to each biweekly payment, or apply a single one-time principal payment.

Updated Nov 21, 2025

Standard amortization with an additional fixed payment added every month.

Inputs

Results

Updates as you type

Months to payoff

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Years to payoff

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Total interest paid

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Interest saved

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OutputValueUnit
Months to payoff—months
Years to payoff——
Total interest paid—USD
Interest saved—USD
Primary result—

Visualization

Methodology

Monthly scenarios use standard fixed-rate amortization formulas to compute the scheduled payment and then recompute payoff time when a fixed extra amount is added each month. For interest rate conversions and period counts we use nominal APR divided by the number of periods per year.

Biweekly scenarios model 26 equal periods per year. A true biweekly strategy can reduce interest faster because there are 26 payments versus 12; this model treats the biweekly payment as a separate schedule with its own per-period rate.

One-time principal reductions subtract the payment from principal immediately and then compute the remaining schedule using the same nominal monthly interest rate and remaining term (unless you choose to recast payments).

Key takeaways

Choose the method that matches how you will actually make extra payments: monthly extras, biweekly additions, or a single one-time payment.

Results are estimates; verify with your loan servicer before changing payment arrangements. This tool adheres to standard numeric methods and cites standards organizations for transparency.

Further resources

Expert Q&A

Will extra payments always reduce my interest?

Yes, when applied to principal they reduce the principal balance sooner and therefore reduce total interest. The amount of savings depends on timing, frequency, and whether your servicer applies payments to principal immediately.

Is biweekly always better than monthly?

Biweekly schedules often accelerate payoff because 26 payments/year typically equals 13 monthly payments' worth across a year. Actual benefit depends on whether your servicer applies biweekly payments as they arrive or holds them.

Can this tool model income-driven repayment or forgiveness programs?

No. This calculator models fixed-rate amortization only. Income-driven repayment, deferment, or forgiveness programs are governed by program rules and can change amortization behavior; consult your loan servicer or plan documents.

How accurate are the numbers?

These are mathematical estimates based on inputs you provide. They assume fixed nominal APR and standard compounding aligned to payment frequency. Real-world factors such as rounding rules, payment application timing, fees, and servicer policies can change results.

Sources & citations