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.
Standard amortizing loan using 12 payments per year. Calculates base payment and optional extra payment effect.
Inputs
Results
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%
| Output | Value | Unit |
|---|---|---|
| Payment per period (includes extras) | -$1.35 | USD |
| Base payment (no extras) | -$1.35 | USD |
| Total paid | -$162.50 | USD |
| Total interest | -$30,162.50 | USD |
| Effective annual rate (EAR) | 1000.00% | % |
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).
Further resources
Expert Q&A
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
- National Institute of Standards and Technology (NIST) — Numerical Methods and Validation — https://www.nist.gov
- International Organization for Standardization (ISO) — Standards and accuracy guidance — https://www.iso.org
- Institute of Electrical and Electronics Engineers (IEEE) — Software and numerical best practices — https://www.ieee.org
- Occupational Safety and Health Administration (OSHA) — Noting standards compliance for testing environments — https://www.osha.gov
- Consumer Financial Protection Bureau — Loan and APR disclosures — https://www.consumerfinance.gov