Boat Loan Calculator

Calculate monthly payments, total interest, and total cost for financing a boat purchase.

Inputs

Boat Price

Down Payment

Interest Rate

Loan Term

years

Tab to move between fields

Results

Monthly Payment

$427.33

≈ 8 tanks of gas

Total Cost

$60,279.16

≈ 5 years of state college

Total Interest$15,279.16

Loan Amount$36,000.00

Loan-to-Value80%

Down Payment20%

Total Payments$51,279.16

Amortising loan payment

1.Convert the annual rate to a monthly rate
$i = annual rate / 12$
Payments are monthly, so every term in the formula has to be expressed per month.
2.Count the payments
$n = years * 12$
The number of monthly payments over the whole term.
3.Solve for the level payment
$M = P*i*(1+i)^n / ((1+i)^n - 1)$
This comes from setting the present value of all n equal payments equal to the amount borrowed, then solving for the payment. The (1+i)ⁿ − 1 in the denominator is the sum of a geometric series — the same series that drains a pension or decays a drug in plasma, which is why one formula family serves calculators across several hubs.

Simon Stevin published the first printed interest tables, including the present value of an annuity — the relationship this payment formula inverts. Until then such tables were guarded as trade secrets by lenders.

Simon Stevin, Tafelen van Interest, Antwerp·1582

How to Use This Calculator

Enter the boat price and your down payment in dollars.
Input the annual interest rate (%) and loan term in years from your lender.
Review the monthly payment and total interest costs in the results.
Adjust the down payment or loan term to find a payment that fits your budget.
Check the loan-to-value (LTV) ratio — lenders typically require LTV below 80-85%.

How the result changes with Boat Price

Boat Price	Monthly Payment	Total Cost
1,000,900	$11,774.03	$1,421,883.42
3,500,650	$41,446.50	$4,982,580.39
6,500,350	$77,053.47	$9,255,416.75
9,000,100	$106,725.95	$12,816,113.72

What each input means

Boat Price: Purchase price of the boat.
Down Payment: Amount paid upfront toward the purchase.
Interest Rate: Annual interest rate on the boat loan.
Loan Term: Length of the loan in years.

How this is calculated

Worked example, using the default values

Identify Input Parameters
4 parameters
Boat Price = 45000, Down Payment = 9000, Interest Rate = 7.5, Loan Term = 10 = 4 input(s) provided
Calculate Monthly Payment
Monthly Payment
427.33 = $427.33
Calculate Total Cost
Total Cost
60279.16 = $60,279.16
Calculate Total Interest
Total Interest
15279.16 = $15,279.16
Calculate Loan Amount
Loan Amount
36000 = $36,000