Fidamen

Boat Loan APR Calculator

This calculator compares monthly and bi-weekly amortizing schedules for a boat loan. Enter the loan principal, APR, term, and optional extra payments to see periodic payment, total interest, total paid, and effective annual rate.

Bi-weekly schedules generally use 26 payments per year (52 weeks ÷ 2). Results assume an amortizing installment loan where interest compounds at the periodic rate implied by the APR and where fees are either entered separately or omitted from nominal APR calculations.

Updated Nov 17, 2025QA PASS — golden 25 / edge 120Run golden-edge-2026-01-23

Governance

Record 911677b58963 • Reviewed by Fidamen Standards Committee

Standard amortizing loan using 12 payments per year. Calculates base payment and optional extra payment effect.

Inputs

Results

Updates as you type

Payment per period (includes extras)

-$1.35

Base payment (no extras)

-$1.35

Total paid

-$162.50

Total interest

-$30,162.50

Effective annual rate (EAR)

1000.00%

OutputValueUnit
Payment per period (includes extras)-$1.35USD
Base payment (no extras)-$1.35USD
Total paid-$162.50USD
Total interest-$30,162.50USD
Effective annual rate (EAR)1000.00%%
Primary result-$1.35

Visualization

Methodology

Calculations use standard annuity formulas for fixed-rate amortizing loans. Periodic interest rate = APR / payment periods per year. Base payment is the annuity payment solving principal = payment * (1 - (1 + r)^-n) / r.

For bi-weekly mode this tool uses 26 payments per year. Effective annual rate (EAR) is computed as (1 + periodic_rate)^(payments_per_year) - 1 to show compounding effect of the chosen payment frequency.

Numeric validation and rounding follow best practices for financial calculators. Results are presented in currency rounded to two decimals and rates to at least two decimal places. See citations for standards on numerical accuracy and validation.

Worked examples

Example: $30,000 principal, 6.5% APR, 10 years. Monthly base payment uses payments_per_year = 12 and yields base payment per month. Bi-weekly uses payments_per_year = 26 and yields smaller per-period payment but more frequent payments; total interest may be lower due to extra periods.

If you enter an extra payment per period, this is added to each scheduled payment and reduces total interest and the effective payoff duration. This calculator shows total interest under the schedule but does not adjust n dynamically to show early payoff date (it reports totals assuming full scheduled periods are paid).

F.A.Q.

Does bi-weekly always save interest compared with monthly?

Not always. Savings come from the increased number of compounding/repayment events (26 vs 12) and how the lender applies payments. If a lender simply divides a monthly payment into two equal halves but only posts 24 payments per year, there may be no savings. This tool assumes 26 posted payments per year.

Is APR the same as the interest rate?

APR is the annual percentage rate that typically represents the nominal interest cost per year. APR may or may not include certain fees depending on jurisdiction and lender disclosures. Use the 'fees' field to note upfront charges; consult your loan documents for the lender's disclosed APR.

How accurate are the results?

Results use standard annuity math and are rounded for display. They are estimates and may differ from lender schedules due to rounding conventions, payment posting rules, compounding method, and fees. See the accuracy and standards citations.

Can this calculator compute an exact APR from payment history or fees?

This tool computes payments from an APR, not the reverse. Exact APR calculation from cash flows requires an internal rate of return/root-finding procedure and full disclosure of all charges; use a dedicated APR solver for that purpose.

Sources & citations

Further resources

External guidance

Versioning & Change Control

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

Record ID: 911677b58963

What changed (latest)

v1.0.0 • 2025-11-17 • 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 17, 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 • 2025-11-17 • 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: 818e4a68d5d6