Boat Loan Calculator what a 15-year term costs
Enter the price, any deposit, the rate and the term. You get the monthly payment, the amount financed and the interest a long marine term adds.
Marine Terms Run Long
Boat loans are commonly written over 10 to 20 years, far longer than car finance.
Mooring and Upkeep Excluded
Insurance, berthing, winter storage, haul-out and servicing sit outside this payment.
What is a boat loan calculator?
At a Glance
A boat loan calculator turns a purchase price, a deposit, an interest rate and a term into a monthly payment, and shows the number that the long terms in marine finance make surprisingly large: the total interest. A boat loan is usually secured against the vessel, which is why the rate is lower than an unsecured loan — and why lenders are willing to write it over so many years.
A marine loan is an ordinary annuity: the same payment every month, each one covering the interest accrued since the last and putting whatever is left against the balance.
M = P × i × (1 + i)ⁿ ÷ ((1 + i)ⁿ − 1)P is the amount financed after your deposit and any trade-in, i is the annual rate divided by twelve, and n is the number of monthly payments. According to the Consumer Financial Protection Bureau's guidance on vehicle finance, the term is what drives the total interest even more than the rate — and marine terms are among the longest written on a movable asset.
This calculator reports principal and interest only. Insurance, berthing or mooring fees, winter storage, haul-out, antifouling and servicing are all substantial ongoing costs of ownership, but none of them is part of the loan.
These are the values the calculator loads by default.
Work out what is financed
With no deposit, the full 45,000 is financed. Every unit put down comes straight off this figure.
Turn the rate into a monthly rate
7.99 % ÷ 12 = 0.66583 % per month, across 15 × 12 = 180 payments.
Apply the annuity formula
The payment is 429.78 a month — modest enough that the term rarely gets questioned at the point of sale.
Add up the interest
180 × 429.78 = 77,361 repaid on a 45,000 boat. Interest: 32,361 — 72 % of the purchase price.
Compare a 10-year term
The same loan over 10 years costs 545.74 a month — 116 more — and just 20,488 in interest. Five fewer years saves 11,873.
The payment decides whether you can afford the boat this month. The interest and the upkeep decide whether you can afford it for fifteen years.
The term dominates the total. Same 45,000 at 7.99 %:
- 10 years → 545.74/month, 20,488 interest
- 15 years → 429.78/month, 32,361 interest
- 20 years → 376.12/month, 45,268 interest
Going from 10 to 20 years saves 170 a month and costs 24,780 more.
Upkeep often rivals the payment. A common rule of thumb in the marine trade puts annual running costs at a meaningful percentage of the vessel's value once berthing, insurance, winter storage and servicing are added up. Treat the loan payment as a floor for what ownership costs, not a ceiling.
Long terms and depreciation do not mix well. A boat financed over 20 years repays very little principal in the early years, so the balance can sit above the resale value for a long time. That matters the moment you want to sell or trade up.
For the schedule payment by payment, use the Amortization Schedule Calculator. For the same maths on a motorhome, use the RV Loan Calculator.
What this estimate does and does not include
This calculator is for informational purposes and assumes a fixed rate, equal monthly payments and no fees.
- Fees change the APR. Documentation, survey and origination fees raise the APR above the nominal rate. Compare offers on APR.
- Running costs are excluded. Berthing, insurance, winter storage, haul-out and servicing are ongoing and often large.
- Depreciation is excluded. It is not part of the loan but it is part of the cost of ownership.
- Rates here are illustrative. Marine rates depend on the lender, your credit, the age and type of vessel, and whether a survey is required — use a real quote.
- Prepayment terms vary. Some agreements charge for early repayment.
Verify the payment against the lender's binding offer, and consult a qualified financial advisor before committing to a long term on a depreciating asset.