Authoritative Data Source & Methodology

AuthoritativeDataSource: Consumer Financial Protection Bureau (CFPB) — “What is amortization and how could it affect my auto loan?” (Sept 25, 2024). Tutti i calcoli si basano rigorosamente sulle formule e sui dati forniti da questa fonte.

The formula explained

Let:

  • P_f = amount financed
  • r = APR per period (APR / periods per year)
  • n = number of periods

Payment per period:

 \( \text{Pay} = \dfrac{P_f \cdot r}{1 - (1 + r)^{-n}} \)

Interest each period is computed on the declining balance; schedule rows follow standard amortization where interest = balance × r.

Out-the-door price:

 \( \text{OTD} = (\text{Price} - \text{TradeAdj}) \times (1 + \text{Tax}) + \text{Fees} \)

Trade adjustment:

 \( \text{TradeAdj} = \begin{cases}
              \text{TradeIn}, & \text{if reduce-tax is enabled} \\
              0, & \text{otherwise}
            \end{cases} \)

Equity applied to reduce financing:

 \( \text{Equity} = \max(0, \text{TradeIn} - \text{Payoff}) \)

Amount financed:

 \( P_f = \text{OTD} - \text{Down} - \text{Equity} + \mathbb{1}_{\text{financeFees}}\cdot \text{Fees} \)

Glossary of variables

  • Boat price: Agreed price before tax.
  • Sales tax: Local rate; many regions tax price minus trade-in.
  • Title/registration & dealer fees: Government/dealer charges; optionally financed.
  • Down payment: Cash you pay upfront.
  • Trade-in: Value of your old boat; payoff is what you still owe on it; equity offsets price.
  • Amount financed: What you borrow after all adjustments.
  • APR: Annual Percentage Rate; used to derive per-period rate.
  • Payment frequency: Monthly (12/yr), biweekly (26/yr), weekly (52/yr).

How it works: a step-by-step example

Inputs: Price $45,000; tax 7%; fees $800; down $5,000; trade-in $4,000; payoff $1,000 (equity $3,000); finance fees = Yes; APR 7.49%; term 10 years; monthly.

  1. Taxable base = (45,000 − 4,000) = 41,000 → tax = 0.07 × 41,000 = 2,870.
  2. OTD = 41,000 + 2,870 + 800 = 44,670.
  3. Amount financed = 44,670 − 5,000 − 3,000 + 800 (fees financed) = 37,470.
  4. r = 0.0749 / 12 ≈ 0.0062417; n = 120.
  5. Payment = 37,470 × r / (1 − (1 + r)^−120) ≈ $446. (Your exact result appears above.)

FAQ

Can I model “fees financed” vs. paid upfront?

Yes—toggle “Include fees in the loan.” If off, fees are paid upfront and do not increase the amount financed.

How are biweekly/weekly payments handled?

APR is divided by 26 or 52 for r, and n increases accordingly. The schedule assumes equal periods.

What affects the out-the-door price?

Sales tax policy (trade-in credit), local fees, and dealer charges. Enter your local figures directly.

Is the schedule exact to the day?

It uses equal intervals by frequency. Actual lender day-count may differ slightly; use this as a planning estimate.

Will a higher down payment always lower my payment?

Usually yes because it reduces the amount financed. Use the tool to compare scenarios instantly.

Tool developed by Ugo Candido. Content verified by CalcDomain Editorial Board.
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