Fidamen

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, 2025QA PASS — golden 25 / edge 120Run golden-edge-2026-01-23

Governance

Record 6eecf58c17d1 • Reviewed by Fidamen Standards Committee

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—USD
Months saved—months
Net savings after fees—USD
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.

F.A.Q.

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

Further resources

Versioning & Change Control

Audit record (versions, QA runs, reviewer sign-off, and evidence).

Record ID: 6eecf58c17d1

What changed (latest)

v1.0.0 • 2025-11-05 • MINOR

Initial publication and governance baseline.

Why: Published with reviewed formulas, unit definitions, and UX controls.

Public QA status

PASS — golden 25 + edge 120

Last run: 2026-01-23 • Run: golden-edge-2026-01-23

Engine

v1.0.0

Data

Baseline (no external datasets)

Content

v1.0.0

UI

v1.0.0

Governance

Last updated: Nov 5, 2025

Reviewed by: Fidamen Standards Committee (Review board)

Credentials: Internal QA

Risk level: low

Reviewer profile (entity)

Fidamen Standards Committee

Review board

Internal QA

Entity ID: https://fidamen.com/reviewers/fidamen-standards-committee#person

Semantic versioning

  • MAJOR: Calculation outputs can change for the same inputs (formula, rounding policy, assumptions).
  • MINOR: New features or fields that do not change existing outputs for the same inputs.
  • PATCH: Bug fixes, copy edits, or accessibility changes that do not change intended outputs except for previously incorrect cases.

Review protocol

  • Verify formulas and unit definitions against primary standards or datasets.
  • Run golden-case regression suite and edge-case suite.
  • Record reviewer sign-off with credentials and scope.
  • Document assumptions, limitations, and jurisdiction applicability.

Assumptions & limitations

  • Uses exact unit definitions from the Fidamen conversion library.
  • Internal calculations use double precision; display rounding follows the unit's configured decimal places.
  • Not a substitute for calibrated instruments in regulated contexts.
  • Jurisdiction-specific rules may require official guidance.

Change log

v1.0.0 • 2025-11-05 • MINOR

Initial publication and governance baseline.

Why: Published with reviewed formulas, unit definitions, and UX controls.

Areas: engine, content, ui • Reviewer: Fidamen Standards Committee • Entry ID: 587c1da10662