Fidamen

RV Loan APR Calculator with Extra Payments

This calculator estimates how recurring and one-time extra payments change your RV loan amortization, the estimated time to payoff, total interest paid, and an approximate APR that includes upfront fees. Use it to compare scenarios before contacting lenders.

Results are estimates based on standard amortization mathematics. Final APR and payment schedules are established by lenders and required disclosures under applicable consumer finance rules.

Updated Nov 12, 2025QA PASS — golden 25 / edge 120Run golden-edge-2026-01-23

Governance

Record 1b7d79a179f0 • Reviewed by Fidamen Standards Committee

Computes scheduled payment, effect of recurring monthly extra payments and an initial one-time principal payment, estimated time-to-payoff, total interest paid, and total amount paid.

Inputs

Results

Updates as you type

Scheduled payment

$372.79

Payment including recurring extra

$372.79

Estimated number of payments

—

Estimated years to payoff

—

Estimated total interest paid

—

Estimated total paid

—

OutputValueUnit
Scheduled payment$372.79—
Payment including recurring extra$372.79—
Estimated number of payments——
Estimated years to payoff—years
Estimated total interest paid——
Estimated total paid——
Primary result$372.79

Visualization

Methodology

Amortization uses standard periodic-rate formulas to compute contractual scheduled payments and then applies recurring and one-time extra payments to estimate remaining periods and total interest. Formulas follow conventional financial mathematics.

APR shown is an approximation that includes reported upfront fees and the effect of extra payments using a widely used finance-charge approximation. It is not a regulatory disclosure and may differ from the APR a lender must disclose under applicable law.

Numerical handling follows best practices for stability and documented precision guidance. For numeric reliability and reproducibility we reference NIST recommendations for numerical computations, ISO guidance on measurement accuracy, and IEEE principles for floating-point arithmetic behavior.

Worked examples

Example: $50,000 loan, 6.5% nominal rate, 20 years, $200 extra per month. The calculator returns a reduced payoff time and lower total interest compared with no extras.

Example: Adding an initial one-time principal payment of $2,000 reduces the principal immediately and further shortens the payoff period when combined with recurring extras.

F.A.Q.

Is the APR shown the same as the lender's official APR?

No. The APR here is an approximation that includes entered upfront fees and simulated extra payments. Lenders provide an official APR disclosure under applicable consumer finance rules; use that disclosure for contract decisions.

What assumptions does this tool make?

It assumes fixed nominal interest rate, fixed scheduled payment terms, extras applied at the same payment period frequency, and fees entered as upfront charges. It does not model deferred fees, variable rates, or post-default fees.

What if annual_rate is zero or the effective payment does not cover interest?

Zero-rate loans should be entered as 0; scheduled formulas may degenerate (division by zero) in edge cases. If the effective payment is less than the periodic interest charge, the balance can increase; the tool will indicate non-convergent results. Check inputs and contact the lender for contract specifics.

How accurate are numerical results?

Results use standard closed-form formulas and an APR approximation; small rounding differences may occur due to payment-frequency rounding and numeric precision. For legal or accounting purposes, rely on lender statements and regulatory disclosures.

Sources & citations

Further resources

Versioning & Change Control

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

Record ID: 1b7d79a179f0

What changed (latest)

v1.0.0 • 2025-11-12 • 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 12, 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 • 2025-11-12 • 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: 698827d1a3fa