Fidamen

Boat Loan Payment Calculator with Bi-Weekly Payments

This calculator compares monthly and bi‑weekly repayment plans for a boat loan. It supports true bi‑weekly amortization (26 payments per year) and accelerated bi‑weekly payments by splitting the monthly payment in half.

Enter the loan amount, APR, term, and any recurring extra payment. Results show scheduled payment amounts, number of payments, total paid and total interest for each method so you can compare cost and payoff speed.

Updated Nov 10, 2025QA PASS — golden 25 / edge 120Run golden-edge-2026-01-23

Governance

Record 7ca91f312002 • Reviewed by Fidamen Standards Committee

Amortization with payments every two weeks (26 payments per year). Uses the bi‑weekly periodic rate to compute level payments over the total 26*years periods.

Inputs

Results

Updates as you type

Bi‑weekly payment

$30,468.75

Bi‑weekly payment (with extra)

$30,468.75

Payments (count)

130

Total paid over life of loan

$3,960,937.50

Total interest paid

$3,930,937.50

Effective annual rate (EAR)

2400.00%

OutputValueUnit
Bi‑weekly payment$30,468.75USD
Bi‑weekly payment (with extra)$30,468.75USD
Payments (count)130—
Total paid over life of loan$3,960,937.50USD
Total interest paid$3,930,937.50USD
Effective annual rate (EAR)2400.00%%
Primary result$30,468.75

Visualization

Methodology

Monthly method uses standard amortization with 12 periods per year and converts the nominal APR to a monthly periodic rate.

True bi‑weekly method converts the nominal APR to a bi‑weekly periodic rate (divide APR by 26) and amortizes over 26 × years periods.

Split bi‑weekly method takes the monthly amortized payment and pays half every two weeks (26 payments/year), often creating an accelerated payoff because 26 half‑monthly payments exceed 12 full monthly payments.

Key takeaways

Use the monthly method to see lender‑standard amortization. Use true bi‑weekly or split bi‑weekly to compare accelerated payoff options.

This calculator provides estimates; consult your lender for precise schedules, fees, and the exact application of payments.

Worked examples

Example: $30,000 loan, 6% APR, 5 years. Monthly payment ≈ calculated using APR/12. True bi‑weekly payment uses APR/26 and 130 payments over 5 years.

If you split monthly payment in half and pay bi‑weekly, you typically make the equivalent of 13 monthly payments per year (26 half payments), which reduces principal faster and lowers total interest.

F.A.Q.

Is bi‑weekly always cheaper than monthly?

True bi‑weekly schedules and split‑monthly schedules can reduce interest compared to monthly payments because they increase the number of payments per year (26 vs 12). Savings depend on interest rate, term, and whether your lender applies payments immediately to principal.

What is the difference between APR and effective annual rate (EAR)?

APR is the nominal annual rate often used for disclosure. EAR accounts for compounding within the year and shows the annualized effect: EAR = (1 + periodic_rate)^(periods_per_year) - 1.

Do results match my lender's statements exactly?

This tool uses standard annuity formulas and assumes payments are applied immediately and without fees. Lenders may use different day‑count conventions, rounding rules, timing, or fees that change results. Use this calculator for estimates and comparison only.

How should I enter extra payments?

Enter recurring extra principal paid each scheduled period. One‑time lump sums are not modeled here and must be applied separately or with a full amortization schedule tool.

What rounding or precision is used?

Displayed results are rounded for presentation. Internal calculations assume exact arithmetic; small differences can occur due to rounding in lender schedules.

Sources & citations

Further resources

Versioning & Change Control

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

Record ID: 7ca91f312002

What changed (latest)

v1.0.0 • 2025-11-10 • 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 10, 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 • 2025-11-10 • 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: 792bb8d3a285