Fidamen

Boat Loan Interest Calculator with Bi-Weekly Payments

This calculator estimates periodic payments and total cost for a boat loan when payments are made on a bi-weekly schedule (26 payments per year). Enter the financed amount, APR, term, and any optional extra payments to see scheduled payment amounts and an approximate total interest cost over the scheduled term.

The tool uses standard loan amortization mathematics to produce per-period payment values and basic aggregates. It provides an equivalent monthly estimate for budgeting, and includes accuracy notes on rounding and extra-payment effects.

Updated Nov 8, 2025QA PASS — golden 25 / edge 120Run golden-edge-2026-01-23

Governance

Record 823c50246256 • Reviewed by Fidamen Standards Committee

Inputs

Results

Updates as you type

Payment per period (before extra)

$235.59

Payment per period (including extra)

$235.59

Number of scheduled payments

260

Total paid over scheduled term (incl. extras)

$61,252.62

Total interest paid (approx., scheduled term)

$16,252.62

Equivalent monthly payment (approx.)

$510.44

OutputValueUnit
Payment per period (before extra)$235.59USD
Payment per period (including extra)$235.59USD
Number of scheduled payments260—
Total paid over scheduled term (incl. extras)$61,252.62USD
Total interest paid (approx., scheduled term)$16,252.62USD
Equivalent monthly payment (approx.)$510.44USD
Primary result$235.59

Visualization

Methodology

We compute the periodic interest rate by dividing the annual percentage rate (APR) by the number of payments per year. The scheduled payment formula is the standard annuity payment formula applied to the chosen periodic rate and total number of scheduled periods.

If extra payments are entered, the calculator adds the extra amount to each scheduled payment and calculates totals assuming the same number of scheduled payments. This provides an upper-bound estimate of total paid and interest; making extra payments typically shortens the loan and reduces total interest but requires an amortization schedule to compute the exact shortened term.

F.A.Q.

Does bi-weekly payment schedule reduce total interest?

Bi-weekly schedules can reduce total interest compared with monthly payments when the payment cadence results in more frequent principal reduction (for example, 26 bi-weekly payments vs 12 monthly). This calculator shows scheduled-term aggregates; if extra payments shorten the term, total interest will be lower than the 'scheduled' estimate here.

Are results exact for extra payments that change term length?

No. For exact remaining-term calculations and precise interest savings from extra payments, a full amortization schedule that re-computes balance and term after each extra payment is required. This tool provides accurate scheduled-term math but treats extras as applied each period without re-amortizing the schedule.

How do rounding and numeric precision affect results?

Results are subject to floating-point rounding and formatting. IEEE 754 floating-point behavior and local currency rounding rules can cause cent-level differences. See the accuracy caveats and standards citations below.

Is APR the same as periodic rate?

APR is an annual percentage rate; the periodic rate used in the payment formula is APR divided by the number of payments per year. This tool uses the nominal APR supplied by the user and does not derive APR from payment history or fees beyond the 'fees' input.

Sources & citations

Further resources

Versioning & Change Control

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

Record ID: 823c50246256

What changed (latest)

v1.0.0 • 2025-11-08 • 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 8, 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 • 2025-11-08 • 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: a41abe7487ff