Fidamen

Auto Loan Refinance Calculator with Bi-Weekly Payments

This tool compares your current auto loan to a refinance offer, supporting monthly and bi-weekly payment schedules. It estimates periodic payments, total cost, and how long it takes to recover refinance fees (break-even).

Results are estimates based on standard amortization formulas and the inputs you provide. Use the calculator for planning and disclosure; confirm exact figures with the lender before refinancing.

Updated Nov 3, 2025QA PASS — golden 25 / edge 120Run golden-edge-2026-01-23

Governance

Record 8e5cfac3ca4b • Reviewed by Fidamen Standards Committee

Compare your current loan cashflows to a refinance offer. Handles monthly and bi-weekly frequencies and includes refinance fees in the new principal.

Inputs

Results

Updates as you type

Current periodic payment

$654.72

Refinance periodic payment

$454.18

Total cost remaining (current)

$15,713.21

Total cost (refinance)

$16,350.56

Estimated net interest saved (after fees)

-$1,137.35

Estimated annual cash savings

$2,406.42

Break-even time (years)

0.2078

Break-even time (months)

2

OutputValueUnit
Current periodic payment$654.72USD
Refinance periodic payment$454.18USD
Total cost remaining (current)$15,713.21USD
Total cost (refinance)$16,350.56USD
Estimated net interest saved (after fees)-$1,137.35USD
Estimated annual cash savings$2,406.42USD
Break-even time (years)0.2078years
Break-even time (months)2months
Primary result$654.72

Visualization

Methodology

We model both loans as fully amortizing fixed-rate loans. The periodic payment formula used is the standard annuity payment: payment = r * PV / (1 - (1 + r)^-n), where r is the periodic interest rate and n is the number of periods.

Bi-weekly schedules are treated as 26 payments per year; monthly schedules as 12. Refinance fees are added to the new principal for a conservative estimate of new payments and total cost.

Key takeaways

This calculator provides a conservative, transparent estimate to compare your current auto loan to a refinance offer with support for monthly or bi-weekly payments.

Always verify numbers with your lender and review loan documents for application-specific rules such as payment posting, rounding, and prepayment penalties.

F.A.Q.

Why does switching to bi-weekly payments often reduce interest?

Bi-weekly schedules create effectively one extra monthly payment per year (26 bi-weekly payments ≈ 13 monthly payments). Making payments more frequently reduces the outstanding principal sooner, lowering total interest if the lender applies payments immediately to principal.

Do results include taxes, insurance, or penalties?

No. This calculator estimates principal and interest only. It does not include taxes, insurance, dealer add-ons, mandatory escrow amounts, or lender-specific fees beyond the refinance fees you enter. Check loan documents for those items.

How accurate are the numbers?

Estimates use standard amortization math and are accurate to normal rounding. Differences can arise due to lender rounding rules, exact payment dates, interest accrual conventions, payment processing timing, and any prepayment or recasting policies. For regulatory and measurement guidance, users may consult standards from NIST and ISO for uncertainty considerations.

Sources & citations

Further resources

External guidance

Versioning & Change Control

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

Record ID: 8e5cfac3ca4b

What changed (latest)

v1.0.0 • 2025-11-03 • 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 3, 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 • 2025-11-03 • 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: 5c170f36cbd8