{
  "id": "boat-loan",
  "version": "6d6a0a9fabcf",
  "status": "published",
  "name": "Boat Loan Calculator",
  "question": "What will my boat loan cost?",
  "summary": "Computes the monthly payment, total interest, payoff date, and full payment schedule of a fixed-rate loan for the boat.",
  "category": "finance",
  "subcategory": "loans",
  "url": "https://www.acalculator.org/finance/boat-loan-calculator",
  "markdown": "https://www.acalculator.org/finance/boat-loan-calculator.md",
  "kind": "schedule",
  "method": "payment = L × r ÷ (1 − (1 + r)^−n), with L the amount borrowed, r the APR ÷ 12, and n the number of months; each month, interest = balance × r and the rest of the payment lowers the balance.",
  "assumptions": [
    "The rate is fixed for the whole loan and interest is charged monthly at APR ÷ 12.",
    "Payments are made at the end of each month, starting one month after the start date.",
    "Sales tax is charged on the price minus the trade-in value, as most US states do.",
    "Extra payments go straight to the balance; the last payment is whatever is left.",
    "Values are not rounded to the cent between months; only the display is rounded."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "price": {
        "title": "Price of the boat",
        "description": "The price of the boat before tax and fees.",
        "type": "number",
        "x-unit": "USD",
        "minimum": 0,
        "maximum": 100000000
      },
      "down": {
        "title": "Cash down",
        "description": "The cash you pay up front, which lowers the amount you borrow.",
        "type": "number",
        "x-unit": "USD",
        "minimum": 0,
        "maximum": 100000000
      },
      "trade": {
        "title": "Trade-in value",
        "description": "What the dealer pays for your current vehicle. It lowers the amount you borrow and the taxed price.",
        "type": "number",
        "x-unit": "USD",
        "minimum": 0,
        "maximum": 100000000
      },
      "rate": {
        "title": "Interest rate (APR)",
        "description": "The yearly interest rate of the loan. The monthly rate is this divided by 12.",
        "type": "number",
        "x-unit": "percent",
        "minimum": 0,
        "maximum": 50
      },
      "start": {
        "title": "Loan start date",
        "description": "The day the loan starts. The first payment is one month later. Leave it empty to number the payments without dates.",
        "type": "string",
        "format": "date"
      },
      "term": {
        "title": "Length of loan (months)",
        "description": "The number of monthly payments, from 1 to 240.",
        "type": "integer",
        "minimum": 1,
        "maximum": 240
      },
      "tax": {
        "title": "Sales tax rate",
        "description": "The sales tax rate, charged on the price minus the trade-in value.",
        "type": "number",
        "x-unit": "percent",
        "minimum": 0,
        "maximum": 25
      },
      "fees": {
        "title": "Dealer and registration fees",
        "description": "Fees and add-ons charged on top of the price, for example documentation and registration.",
        "type": "number",
        "x-unit": "USD",
        "minimum": 0,
        "maximum": 1000000
      },
      "taxin": {
        "title": "Roll tax and fees into the loan",
        "description": "When on, the sales tax and fees are borrowed. When off, you pay them up front.",
        "type": "boolean"
      },
      "extra": {
        "title": "Extra each month",
        "description": "An extra amount paid with every payment. It goes straight to the balance.",
        "type": "number",
        "x-unit": "USD",
        "minimum": 0,
        "maximum": 1000000
      }
    }
  },
  "outputs": {
    "payment": {
      "label": "Your monthly payment",
      "description": "The level monthly payment that repays the loan over its length, without extra payments.",
      "format": "money"
    },
    "payments": {
      "label": "Number of payments",
      "description": "How many monthly payments it takes to repay the loan, with any extra payments.",
      "format": "integer"
    },
    "payoff": {
      "label": "Paid off in",
      "description": "The month of the last payment, when a start date is given.",
      "format": "month-year"
    },
    "each": {
      "label": "You pay each month",
      "description": "The monthly payment plus any extra amount. The last payment is whatever is left, so it can be smaller.",
      "format": "money"
    },
    "span": {
      "label": "Payments last",
      "description": "How many months of payments it takes to repay the loan, with any extra payments.",
      "format": "duration"
    },
    "amount": {
      "label": "Loan",
      "description": "The amount borrowed: price minus cash down and trade-in, plus tax and fees when rolled in.",
      "format": "money"
    },
    "interest": {
      "label": "Interest",
      "description": "All the interest paid over the life of the loan.",
      "format": "money"
    },
    "paid": {
      "label": "Total you’ll repay",
      "description": "The amount borrowed plus all the interest.",
      "format": "money"
    },
    "upfront": {
      "label": "Paid up front",
      "description": "Cash down, plus the sales tax and fees when they are not rolled into the loan.",
      "format": "money"
    },
    "cost": {
      "label": "What the boat really costs",
      "description": "The price plus sales tax, fees, and all the interest.",
      "format": "money"
    },
    "saved": {
      "label": "Interest saved by paying extra",
      "description": "The interest the extra monthly amount saves, compared with no extra payments.",
      "format": "money"
    },
    "sooner": {
      "label": "Months saved by paying extra",
      "description": "How many months sooner the loan is paid off with the extra monthly amount.",
      "format": "integer"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "price": 100000,
      "down": 20000,
      "trade": 0,
      "rate": 5,
      "start": "2026-10-05",
      "term": 120,
      "tax": 0,
      "fees": 0,
      "taxin": true,
      "extra": 0
    },
    "outputs": {
      "payment": 848.5241219126018,
      "payments": 120,
      "payoff": "2036-10-05",
      "each": 848.5241219126018,
      "span": {
        "months": 120
      },
      "amount": 80000,
      "interest": 21822.89462951221,
      "paid": 101822.89462951222,
      "upfront": 20000,
      "cost": 121822.89462951222
    },
    "text": "Borrowing $80,000.00 at 5% APR over 120 months costs $848.52 a month, with $21,822.89 of interest in total."
  },
  "examples": [
    {
      "given": {
        "price": 40000,
        "down": 8000,
        "trade": 0,
        "rate": 7.5,
        "term": 72,
        "start": "2026-10-01"
      },
      "expect": {
        "amount": 32000,
        "payment": 553.2835934177308,
        "interest": 7836.4187260771805,
        "payoff": "2032-10-01"
      },
      "source": "hand calculation in content.mdx, checked in Python (docs/progress/WP-21/python/asset_loans.py); Consumer Financial Protection Bureau, Can I prepay my loan at any time without penalty? https://www.consumerfinance.gov/ask-cfpb/can-i-prepay-my-loan-at-any-time-without-penalty-en-843/"
    },
    {
      "given": {
        "price": 100000,
        "down": 20000,
        "trade": 0,
        "rate": 5,
        "term": 120,
        "start": "2026-10-01"
      },
      "expect": {
        "amount": 80000,
        "payment": 848.5241219126042,
        "interest": 21822.894629512142,
        "payoff": "2036-10-01"
      },
      "source": "hand calculation in content.mdx, checked in Python (docs/progress/WP-21/python/asset_loans.py); Consumer Financial Protection Bureau, Can I prepay my loan at any time without penalty? https://www.consumerfinance.gov/ask-cfpb/can-i-prepay-my-loan-at-any-time-without-penalty-en-843/"
    },
    {
      "given": {
        "price": 100000,
        "down": 20000,
        "trade": 0,
        "rate": 5,
        "term": 240,
        "start": "2026-10-01"
      },
      "expect": {
        "payment": 527.9645913733269,
        "interest": 46711.50192959798,
        "payoff": "2046-10-01"
      },
      "source": "hand calculation in content.mdx, checked in Python (docs/progress/WP-21/python/asset_loans.py); Consumer Financial Protection Bureau, Can I prepay my loan at any time without penalty? https://www.consumerfinance.gov/ask-cfpb/can-i-prepay-my-loan-at-any-time-without-penalty-en-843/"
    },
    {
      "given": {
        "price": 25000,
        "down": 0,
        "trade": 0,
        "rate": 0,
        "term": 60,
        "start": "2026-10-01"
      },
      "expect": {
        "payment": 416.6666666666667,
        "interest": 0,
        "paid": 25000
      },
      "source": "hand calculation in content.mdx: at 0% APR the payment is 25,000 ÷ 60; Consumer Financial Protection Bureau, Can I prepay my loan at any time without penalty? https://www.consumerfinance.gov/ask-cfpb/can-i-prepay-my-loan-at-any-time-without-penalty-en-843/"
    }
  ],
  "sources": [
    "IRS Publication 936, Home Mortgage Interest Deduction (a home includes a boat with sleeping, cooking, and toilet facilities). https://www.irs.gov/publications/p936",
    "Consumer Financial Protection Bureau, Can I prepay my loan at any time without penalty? https://www.consumerfinance.gov/ask-cfpb/can-i-prepay-my-loan-at-any-time-without-penalty-en-843/",
    "Amortized loan payment (annuity) formula: S. A. Broverman, Mathematics of Investment and Credit, chapter 3 (loan payment and amortization schedule)."
  ],
  "related": [
    "auto-loan",
    "rv-loan",
    "compound-interest"
  ],
  "changelog": [
    {
      "date": "2026-09-29",
      "note": "Worked examples name a published reference for their rule."
    },
    {
      "date": "2026-10-01",
      "note": "The answer sentence states what you pay each month with any extra payment (new “You pay each month” and “Payments last” results), and “over 1 month” is singular."
    }
  ]
}