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Simple Calculators

Boat Loan Calculator

Estimate your monthly boat payment, amount financed, and total interest

Boat Purchase

Boat, engine, and any trailer bought together

Optional; 0 if none

Applied to the price minus the trade-in

Documentation, title, or registration fees rolled into the loan

The annual rate on your loan offer

1–20 years; longer terms lower the payment but add interest

Related calculators

All finance

Quick summary

A boat loan payment comes from the standard amortization formula applied to the amount financed. In this example, a $45,000 boat with $9,000 down (20%) and 6% sales tax ($2,700) leaves $38,700 to finance. At 8.5% for 15 years (180 payments) that is about $381.09 a month, $29,896.20 in total interest, and a total cost of $77,596.20 including the down payment. These are illustrative figures; enter your own price, tax rate, and loan offer for an estimate.

Reviewed by Simple Calculators TeamLast reviewed

For planning only — not financial or tax advice. Results are estimates based on your inputs and the stated assumptions. Confirm important decisions with a qualified professional.

How to use this calculator

  1. Enter the Boat Price ($), including the engine and trailer if they are sold as a package.
  2. Enter your Down Payment ($) and any Trade-In Value ($) — the down payment's share of the price is shown in the results.
  3. Set Sales Tax (%) for your state and add any documentation, title, or registration costs you are rolling in under Fees Financed ($).
  4. Enter the Interest Rate (%) from your loan offer and the Loan Term (years), from 1 to 20.
  5. Read the monthly payment, amount financed, total interest, and total cost, and check the principal vs interest bar.
  6. Try a shorter Loan Term (years) or a larger Down Payment ($) to see how much interest you could save.

Boat Loan Formulas

Sales Tax

T=(P−Vtrade)×t100T = (P - V_{\text{trade}}) \times \frac{t}{100}
P
Boat price
V (trade)
Trade-in value (many states tax only the difference)
t
Sales tax rate in percent

Worked example

A $45,000 boat, no trade-in, 6% sales tax

Given
P = $45,000
V (trade) = $0
t = 6%
Calculation
T=(45,000−0)×0.06T = (45{,}000 - 0) \times 0.06
Result
T = $2,700

Amount Financed

A=P+T+F−D−VtradeA = P + T + F - D - V_{\text{trade}}
F
Fees rolled into the loan (documentation, title, registration)
D
Down payment

Worked example

The same boat with $9,000 down and no financed fees

Given
P + T = $47,700
F = $0
D = $9,000
Calculation
A=45,000+2,700+0−9,000−0A = 45{,}000 + 2{,}700 + 0 - 9{,}000 - 0
Result
A = $38,700

Monthly Payment

M=A×r(1+r)n(1+r)n−1M = A \times \frac{r(1 + r)^{n}}{(1 + r)^{n} - 1}
r
Monthly rate: the annual rate ÷ 12 (8.5% ÷ 12 = 0.0070833)
n
Number of monthly payments: years × 12

Worked example

$38,700 at 8.5% for 15 years (180 payments)

Given
A = $38,700
r = 0.0070833
n = 180
Calculation
M=38,700×0.0070833(1.0070833)180(1.0070833)180−1M = 38{,}700 \times \frac{0.0070833(1.0070833)^{180}}{(1.0070833)^{180} - 1}
Result
M ≈ $381.09 per month

Total Interest

I=M×n−AI = M \times n - A
M
Monthly payment
n
Number of payments
A
Amount financed

Worked example

Interest over the full 15-year term

Given
M = $381.09
n = 180
Calculation
I=381.09×180−38,700I = 381.09 \times 180 - 38{,}700
Result
I = $29,896.20

Frequently asked questions

How is a boat loan payment calculated?

Start with the boat price, add sales tax and any fees you roll into the loan, then subtract your down payment and trade-in to get the amount financed. The monthly payment is that amount spread over the term with the standard amortization formula. In the example, $38,700 at 8.5% for 15 years works out to about $381.09 a month. Your lender's figure may differ slightly because of rounding, the first-payment date, or extra fees.

What costs should I budget for beyond the loan payment?

The loan covers the purchase, not the cost of owning the boat. Plan for boat insurance (lenders usually require it while the loan is open), storage, a slip or mooring if you keep it in the water, trailer upkeep, fuel, routine engine service, winterizing and spring commissioning in colder areas, and safety gear. Add a rough monthly figure for these to the payment shown here to see the full monthly cost.

Do I need a marine survey to finance a boat?

Lenders and insurers often ask for a marine survey, especially for used or larger boats. A surveyor inspects the hull, engine, and systems and estimates the boat's condition and value, which helps confirm that the price is reasonable for the loan. The buyer usually pays for it, so include it in your upfront costs, and ask your lender and insurer what they require before you schedule one.

How do sales tax, title, and registration work for boats?

It depends on your state. Many states tax the price minus any trade-in, which is what this calculator assumes, but some tax the full price, cap the tax, or charge a separate use tax when you register a boat bought elsewhere. Most states require the boat to be registered, and many also title it; larger vessels may be federally documented instead. Check your state's boating agency for the exact rules, and enter any title or registration fees you are financing in Fees Financed ($).

Does the time of year affect a boat purchase?

Boating is seasonal in much of the country. Shopping in the off-season can give you more time to compare boats and negotiate, while buying in spring means you can use the boat right away. Either way, storage costs begin as soon as you own it, and in colder climates you may make payments through months when the boat is laid up, so budget for the full year rather than just the season.

Key terms

Amount Financed
The price plus sales tax and financed fees, minus your down payment and trade-in — the balance you borrow and pay interest on.
Marine Survey
A professional inspection of a boat's condition and value, often requested by lenders and insurers before they approve a loan or policy.
Slip Fee
The charge for keeping a boat in a marina berth, usually billed monthly or by the season, on top of the loan payment.
Amortization
Repaying a loan in equal monthly payments; early payments are mostly interest and later payments are mostly principal.

Methodology, sources & limitations

This page shows the formula, assumptions, and limitations used for this estimate. Rates, thresholds, and other time-sensitive inputs can change, so verify them against the relevant official source before relying on a result.

For our review approach and the primary sources we consult, see the methodology and source policy. If you spot an outdated figure or formula, please contact us with a correction.