Cernarus

Student Loan Refinance Calculator with Extra Payments

This tool helps you compare your existing student loan to a refinance offer and estimate the impact of extra monthly payments. It shows scheduled payments, estimated time to payoff when extra payments are applied, total interest paid, and net savings after refinance fees.

Use realistic numbers for principal, APR, and fees. Results are estimates intended to support decision-making and do not substitute for lender-provided disclosure statements or professional financial advice.

Updated Nov 5, 2025

Compares current plan and refinance plan outputs and shows interest, time, and net savings after fees.

Inputs

Results

Updates as you type

Interest saved

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Months saved

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Net savings after fees

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Approximate break-even (months)

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OutputValueUnit
Interest saved—currency
Months saved—months
Net savings after fees—currency
Approximate break-even (months)—months
Primary result—

Visualization

Methodology

Payments are computed using standard amortization formulas for fixed-rate loans. Monthly interest rate is annual APR divided by 12. Scheduled monthly payment uses the annuity formula.

Time-to-payoff with extra payments is estimated by solving the amortization equation for the number of payments required when monthly payment is increased by the extra monthly amount. When extra payments are zero, time-to-payoff equals the scheduled term.

Quality and numeric handling follow general industry practices: numerical precision expectations are aligned with IEEE 754 floating-point conventions, and development, access control, and data handling follow NIST guidance for secure handling and testing. Quality management for the calculation workflow follows ISO 9001 principles. This tool is informational and not a regulated financial product.

Worked examples

Example: $35,000 current balance at 6.8% for 10 years vs. refinance to 4.5% for 10 years. With no extra payments, compare scheduled payments, total interest, and net savings after any refinance fees.

Example: Adding $50 extra per month often reduces payoff time and interest significantly; run both scenarios with matching extra payments to compare impact.

Further resources

Expert Q&A

Are results exact?

Results are estimates. They assume fixed-rate loans, monthly compounding, and that extra payments are applied monthly against principal. They do not account for variable-rate changes, deferred periods, loan forgiveness programs, income-driven repayment adjustments, or lender-specific rounding rules.

Do you include refinance fees?

Yes. You can enter one-time refinance fees which are added to the refinance scenario when computing net savings and break-even estimates.

What if extra payments are large?

If the extra payment plus scheduled payment would be less than monthly interest (an interest-only or negative amortization case), the model will produce values that indicate payoff is not achieved under those parameters. Adjust inputs or consult your servicer if you see unexpected results.

Is this financial advice?

No. This calculator provides numeric estimates to inform decisions. Consult a qualified financial advisor or your loan servicer before refinancing or changing payments.

Sources & citations