Fidamen

Boat Loan Balloon Payment Calculator with Extra Payments

This calculator computes the periodic payment for a boat loan that includes a balloon payment due at the end of the term, and shows how a constant recurring extra payment per period changes the periodic outflow and estimated payoff time. Use the extra payment fields to model additional principal contributions applied each period.

Outputs include the scheduled periodic payment (excluding extras), the periodic payment with extras, estimated total paid over the term (payments plus balloon), and a simple approximation of periods to payoff if you apply a constant extra payment each period. Results are for planning and comparison only.

Updated Nov 13, 2025QA PASS — golden 25 / edge 120Run golden-edge-2026-01-23

Governance

Record 51b18a0ae046 • Reviewed by Fidamen Standards Committee

Inputs

Results

Updates as you type

Scheduled periodic payment (excl. extras)

-$3.33

Periodic payment including recurring extra

-$3.33

Total paid over term (payments + balloon)

$9,799.94

Total interest paid (estimated)

-$40,200.07

Approx. number of periods to payoff (using constant extra)

-868.2459

OutputValueUnit
Scheduled periodic payment (excl. extras)-$3.33USD
Periodic payment including recurring extra-$3.33USD
Total paid over term (payments + balloon)$9,799.94USD
Total interest paid (estimated)-$40,200.07USD
Approx. number of periods to payoff (using constant extra)-868.2459periods
Primary result-$3.33

Visualization

Methodology

We compute the periodic scheduled payment by solving the present-value annuity equation with a residual balloon balance: principal = payment * (1 - (1+r)^-N)/r + balloon/(1+r)^N, where r is the periodic interest rate and N is the total number of periods.

To illustrate the effect of extra payments we add the recurring extra amount directly to the scheduled payment (this shows the immediate cashflow effect). An approximate analytic formula is used to estimate the number of periods to payoff when a constant extra payment is applied each period; this estimate assumes the extra is applied from the first period it is scheduled and that the interest rate and payment frequency remain constant.

Key takeaways

This calculator is intended for planning and comparison. It uses closed-form formulas to compute scheduled payments for loans with balloon balances and provides a straightforward way to see how recurring extras change cashflow and payoff timing.

For regulatory disclosures, exact payoff schedules, and legal contract terms, rely on lender-provided documents. For auditability and reproducibility, we reference general standards from NIST and ISO for numerical methods and data handling; however, this tool is not a certified financial disclosure instrument.

F.A.Q.

Does this calculator amortize every payment and show a schedule?

This tool computes summary values and an analytic approximation for payoff timing when a constant extra is applied. It does not output a full period-by-period amortization table. For an exact schedule with variable timing of extras, generate an amortization schedule using a spreadsheet or amortization tool that iterates period-by-period.

How accurate are the results if I enter a nonzero extra payment?

The calculator shows the immediate effect of adding a recurring extra payment and gives an analytic estimate of periods-to-payoff. For precise payoff dates and interest savings when extras start or stop mid-term, use a period-by-period amortization engine. See the accuracy notes and standards references below.

Are results compliant with financial disclosure standards?

This calculator provides estimates for planning and comparison only and is not a disclosure of exact finance charges or required periodic payments under consumer protection regulations. Always consult your lender for contractual disclosures and the official loan agreement.

Sources & citations

Further resources

External guidance

Versioning & Change Control

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

Record ID: 51b18a0ae046

What changed (latest)

v1.0.0 • 2025-11-13 • 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 13, 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 • 2025-11-13 • 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: cdfebdec173d