{
  "title": "Balloon payment calculator",
  "human_url": "https://happytails.ai/en/finance-tools/balloon-payment-calculator/",
  "agent_url": "https://happytails.ai/agents/en/finance-tools/balloon-payment-calculator/",
  "language": "en",
  "markdown_url": "https://happytails.ai/en/finance-tools/balloon-payment-calculator.md",
  "content": "Balloon payment calculator\nWork out the balloon left on a loan when regular payments stop before the loan is fully repaid. See the monthly payment, the interest paid, the balloon amount and the final payment, with the full schedule.\nHow can we improve this tool?\nReport a problem or share an idea.\nPlease leave out private information. Your message and the tool name go to our team via PostHog.\nHow to use Balloon payment calculator\nEnter the loan amount and the interest rate.\nChoose whether the payment comes from an amortization term or from a payment you enter.\nEnter the amortization term or the payment, and the month the balloon is due.\nReview the balloon, final payment and totals, then download the JSON report or the monthly CSV.\nUseful next steps\nLoan payment\nMortgage payment\nSimple interest calculator\nMethod\nIn amortization mode the monthly payment is the level payment that would repay the loan over the amortization term, P times r divided by 1 minus (1 + r) to the power of minus n, with r the APR divided by 12. This is the same formula as the spreadsheet PMT function (Microsoft Support, PMT function, checked 16 October 2026). Payments then run until the balloon month, and the balloon is the balance left after the last regular payment. A balloon payment is a large final payment due at the end of a loan, as described by the Consumer Financial Protection Bureau (What is a balloon payment, checked 16 October 2026).\nPayment mode\nWhen you enter the payment yourself, it must be at least one month of interest so the balance never grows. A payment equal to the interest gives an interest-only loan whose balloon is the whole loan amount. If the payments repay the loan before the balloon month, the report shows the payoff month and no balloon.\nRounding and limits\nInterest is rounded to the cent each month, half away from zero, and amounts are exact in minor currency units. When the balloon month equals the amortization term the last payment is adjusted so the balance ends at exactly zero. Fees, rate changes and refinancing are not included. This is a calculation from your own numbers, not financial advice.",
  "content_format": "text/plain",
  "visibility": "public",
  "links": [
    {
      "name": "Loan payment",
      "url": "https://happytails.ai/en/finance-tools/loan-payment/"
    },
    {
      "name": "Mortgage payment",
      "url": "https://happytails.ai/en/finance-tools/mortgage-payment/"
    },
    {
      "name": "Simple interest calculator",
      "url": "https://happytails.ai/en/finance-tools/simple-interest/"
    }
  ],
  "tool": {
    "id": "balloon-payment-calculator",
    "category": "finance-tools",
    "built": true,
    "requirements": "Loan amounts and payments up to 1000000000000 at 0 to 3 decimal places, 100000000000 at 4, 10000000000 at 5 and 1000000000 at 6, with the monthly payment and every month-end balance within 1000000000000000 minor currency units (10000000000000 at 2 decimal places), APRs from 0 to 100 percent, amortization terms and balloon months from 1 to 1200. Calculated locally in your browser. Downloads are a JSON report and a CSV with one row per month.",
    "implementation": {
      "fields": [
        {
          "key": "principal",
          "label": "Loan amount",
          "value": "250000",
          "type": "text",
          "maxLength": 30,
          "help": "The amount borrowed."
        },
        {
          "key": "apr",
          "label": "Interest rate (APR %)",
          "value": "6.5",
          "type": "text",
          "maxLength": 20,
          "help": "From 0 to 100."
        },
        {
          "key": "paymentMode",
          "label": "Monthly payment from",
          "value": "amortization",
          "type": "select",
          "values": [
            "amortization",
            "payment"
          ],
          "labels": {
            "amortization": "An amortization term",
            "payment": "A payment I enter"
          }
        },
        {
          "key": "amortizationMonths",
          "label": "Amortization term (months)",
          "value": "360",
          "type": "text",
          "maxLength": 10,
          "help": "Whole months from 1 to 1200. The payment is set as if the loan ran this long.",
          "showWhen": {
            "paymentMode": [
              "amortization"
            ]
          }
        },
        {
          "key": "payment",
          "label": "Monthly payment",
          "value": "1200",
          "type": "text",
          "maxLength": 30,
          "help": "At least one month of interest on the loan amount.",
          "showWhen": {
            "paymentMode": [
              "payment"
            ]
          }
        },
        {
          "key": "balloonMonth",
          "label": "Balloon due in month",
          "value": "84",
          "type": "text",
          "maxLength": 10,
          "help": "Whole months from 1 to 1200, not later than the amortization term."
        },
        {
          "key": "decimals",
          "label": "Decimal places in amounts",
          "value": "2",
          "type": "select",
          "values": [
            "2",
            "0",
            "1",
            "3",
            "4",
            "5",
            "6"
          ]
        }
      ],
      "registrationFamily": "personal-balance-schedules",
      "input": false,
      "note": "Calculated on your device for balloon months up to 1200 and amounts up to 1000000000000, or less at 4 to 6 decimal places.",
      "experience": {
        "automatic": false,
        "single": false,
        "inputMaxLength": 1000000,
        "inputMode": "text",
        "label": "Loan values",
        "placeholder": "Enter values in the form fields",
        "help": "This calculator reads the form fields below; there is no text box. Up to 1,000,000 characters. Review the settings before running.",
        "action": null
      },
      "mode": "explicit",
      "interactive": false
    },
    "execution": "Browser interface",
    "api": null,
    "browser_agent": {
      "supported": true,
      "name": "run_current_tool",
      "discovery": "WebMCP on the human page in a supporting browser",
      "verification": "See audit/API-AUDIT.md; availability is not verification"
    }
  },
  "markdown": "# Balloon payment calculator\n\n- Human page: https://happytails.ai/en/finance-tools/balloon-payment-calculator/\n- Markdown: https://happytails.ai/en/finance-tools/balloon-payment-calculator.md\n- Structured JSON: https://happytails.ai/agents/en/finance-tools/balloon-payment-calculator/index.json\n- Visibility: public\n\n## Tool capabilities\n\n| Property | Value |\n| --- | --- |\n| Tool ID | `balloon-payment-calculator` |\n| Category | finance-tools |\n| Implementation | Registered implementation. Registration alone is not a production-quality guarantee. |\n| Browser execution | Use the visible action or interactive controls. |\n| Browser processing | Browser; see tool notes for network behavior. |\n| HTTP API | Not callable through HTTP. |\n| Browser-agent interface | run_current_tool |\n\n### Implementation notes\n\nCalculated on your device for balloon months up to 1200 and amounts up to 1000000000000, or less at 4 to 6 decimal places.\n\n### Inputs and settings\n\nNo free-text input is required. Use the file inputs and/or settings below.\n\n| Setting | Meaning | Control type | Default | Constraints |\n| --- | --- | --- | --- | --- |\n| `principal` | Loan amount | text | \"250000\" |  |\n| `apr` | Interest rate (APR %) | text | \"6.5\" |  |\n| `paymentMode` | Monthly payment from | select | \"amortization\" | Allowed: amortization, payment |\n| `amortizationMonths` | Amortization term (months) | text | \"360\" |  |\n| `payment` | Monthly payment | text | \"1200\" |  |\n| `balloonMonth` | Balloon due in month | text | \"84\" |  |\n| `decimals` | Decimal places in amounts | select | \"2\" | Allowed: 2, 0, 1, 3, 4, 5, 6 |\n\n### Browser-agent workflow\n\n1. Open the human page in a browser that supports WebMCP.\n2. Discover the interface exposed by that page; use its actual schema.\n3. Select files on the page first when the tool requires files.\n4. Call `run_current_tool` with valid input and settings.\n5. Inspect the returned result or error and the displayed output. Retrieve files from the displayed download links.\n\nCalls do not automatically copy or download results. Browser permissions still apply. Interface availability alone is not proof of successful execution.\n\n### Planning specification\n\nLoan amounts and payments up to 1000000000000 at 0 to 3 decimal places, 100000000000 at 4, 10000000000 at 5 and 1000000000 at 6, with the monthly payment and every month-end balance within 1000000000000000 minor currency units (10000000000000 at 2 decimal places), APRs from 0 to 100 percent, amortization terms and balloon months from 1 to 1200. Calculated locally in your browser. Downloads are a JSON report and a CSV with one row per month.\n\nThis describes intended requirements. Use the implementation notes, interface schema and observed output to determine current support.\n\n### Complete machine-readable capability record\n\n```json\n{\n  \"id\": \"balloon-payment-calculator\",\n  \"category\": \"finance-tools\",\n  \"built\": true,\n  \"requirements\": \"Loan amounts and payments up to 1000000000000 at 0 to 3 decimal places, 100000000000 at 4, 10000000000 at 5 and 1000000000 at 6, with the monthly payment and every month-end balance within 1000000000000000 minor currency units (10000000000000 at 2 decimal places), APRs from 0 to 100 percent, amortization terms and balloon months from 1 to 1200. Calculated locally in your browser. Downloads are a JSON report and a CSV with one row per month.\",\n  \"implementation\": {\n    \"fields\": [\n      {\n        \"key\": \"principal\",\n        \"label\": \"Loan amount\",\n        \"value\": \"250000\",\n        \"type\": \"text\",\n        \"maxLength\": 30,\n        \"help\": \"The amount borrowed.\"\n      },\n      {\n        \"key\": \"apr\",\n        \"label\": \"Interest rate (APR %)\",\n        \"value\": \"6.5\",\n        \"type\": \"text\",\n        \"maxLength\": 20,\n        \"help\": \"From 0 to 100.\"\n      },\n      {\n        \"key\": \"paymentMode\",\n        \"label\": \"Monthly payment from\",\n        \"value\": \"amortization\",\n        \"type\": \"select\",\n        \"values\": [\n          \"amortization\",\n          \"payment\"\n        ],\n        \"labels\": {\n          \"amortization\": \"An amortization term\",\n          \"payment\": \"A payment I enter\"\n        }\n      },\n      {\n        \"key\": \"amortizationMonths\",\n        \"label\": \"Amortization term (months)\",\n        \"value\": \"360\",\n        \"type\": \"text\",\n        \"maxLength\": 10,\n        \"help\": \"Whole months from 1 to 1200. The payment is set as if the loan ran this long.\",\n        \"showWhen\": {\n          \"paymentMode\": [\n            \"amortization\"\n          ]\n        }\n      },\n      {\n        \"key\": \"payment\",\n        \"label\": \"Monthly payment\",\n        \"value\": \"1200\",\n        \"type\": \"text\",\n        \"maxLength\": 30,\n        \"help\": \"At least one month of interest on the loan amount.\",\n        \"showWhen\": {\n          \"paymentMode\": [\n            \"payment\"\n          ]\n        }\n      },\n      {\n        \"key\": \"balloonMonth\",\n        \"label\": \"Balloon due in month\",\n        \"value\": \"84\",\n        \"type\": \"text\",\n        \"maxLength\": 10,\n        \"help\": \"Whole months from 1 to 1200, not later than the amortization term.\"\n      },\n      {\n        \"key\": \"decimals\",\n        \"label\": \"Decimal places in amounts\",\n        \"value\": \"2\",\n        \"type\": \"select\",\n        \"values\": [\n          \"2\",\n          \"0\",\n          \"1\",\n          \"3\",\n          \"4\",\n          \"5\",\n          \"6\"\n        ]\n      }\n    ],\n    \"registrationFamily\": \"personal-balance-schedules\",\n    \"input\": false,\n    \"note\": \"Calculated on your device for balloon months up to 1200 and amounts up to 1000000000000, or less at 4 to 6 decimal places.\",\n    \"experience\": {\n      \"automatic\": false,\n      \"single\": false,\n      \"inputMaxLength\": 1000000,\n      \"inputMode\": \"text\",\n      \"label\": \"Loan values\",\n      \"placeholder\": \"Enter values in the form fields\",\n      \"help\": \"This calculator reads the form fields below; there is no text box. Up to 1,000,000 characters. Review the settings before running.\",\n      \"action\": null\n    },\n    \"mode\": \"explicit\",\n    \"interactive\": false\n  },\n  \"execution\": \"Browser interface\",\n  \"api\": null,\n  \"browser_agent\": {\n    \"supported\": true,\n    \"name\": \"run_current_tool\",\n    \"discovery\": \"WebMCP on the human page in a supporting browser\",\n    \"verification\": \"See audit/API-AUDIT.md; availability is not verification\"\n  }\n}\n```\n\n## Page guide\n\nWork out the balloon left on a loan when regular payments stop before the loan is fully repaid. See the monthly payment, the interest paid, the balloon amount and the final payment, with the full schedule.\n\nHow can we improve this tool?\n\nReport a problem or share an idea.\n\nPlease leave out private information. Your message and the tool name go to our team via PostHog.\n\n### How to use Balloon payment calculator\n\n1. Enter the loan amount and the interest rate.\n2. Choose whether the payment comes from an amortization term or from a payment you enter.\n3. Enter the amortization term or the payment, and the month the balloon is due.\n4. Review the balloon, final payment and totals, then download the JSON report or the monthly CSV.\n\n## Useful next steps\n\n- [Loan payment](https://happytails.ai/en/finance-tools/loan-payment/) ([Markdown](https://happytails.ai/en/finance-tools/loan-payment.md))\n\n- [Mortgage payment](https://happytails.ai/en/finance-tools/mortgage-payment/) ([Markdown](https://happytails.ai/en/finance-tools/mortgage-payment.md))\n\n- [Simple interest calculator](https://happytails.ai/en/finance-tools/simple-interest/) ([Markdown](https://happytails.ai/en/finance-tools/simple-interest.md))\n\n## Method\n\nIn amortization mode the monthly payment is the level payment that would repay the loan over the amortization term, P times r divided by 1 minus (1 + r) to the power of minus n, with r the APR divided by 12. This is the same formula as the spreadsheet PMT function (Microsoft Support, PMT function, checked 16 October 2026). Payments then run until the balloon month, and the balloon is the balance left after the last regular payment. A balloon payment is a large final payment due at the end of a loan, as described by the Consumer Financial Protection Bureau (What is a balloon payment, checked 16 October 2026).\n\n### Payment mode\n\nWhen you enter the payment yourself, it must be at least one month of interest so the balance never grows. A payment equal to the interest gives an interest-only loan whose balloon is the whole loan amount. If the payments repay the loan before the balloon month, the report shows the payoff month and no balloon.\n\n### Rounding and limits\n\nInterest is rounded to the cent each month, half away from zero, and amounts are exact in minor currency units. When the balloon month equals the amortization term the last payment is adjusted so the balance ends at exactly zero. Fees, rate changes and refinancing are not included. This is a calculation from your own numbers, not financial advice.\n"
}