# Rent versus buy calculator

- Human page: https://happytails.ai/en/finance-tools/rent-versus-buy-calculator/
- Markdown: https://happytails.ai/en/finance-tools/rent-versus-buy-calculator.md
- Structured JSON: https://happytails.ai/agents/en/finance-tools/rent-versus-buy-calculator/index.json
- Visibility: public

## Tool capabilities

| Property | Value |
| --- | --- |
| Tool ID | `rent-versus-buy-calculator` |
| Category | finance-tools |
| Implementation | Registered implementation. Registration alone is not a production-quality guarantee. |
| Browser execution | Use the visible action or interactive controls. |
| Browser processing | Browser; see tool notes for network behavior. |
| HTTP API | Not callable through HTTP. |
| Browser-agent interface | run_current_tool |

### Implementation notes

Calculated on your device for 1 to 50 years with amounts up to 1000000000000, or less at 4 to 6 decimal places.

### Inputs and settings

No free-text input is required. Use the file inputs and/or settings below.

| Setting | Meaning | Control type | Default | Constraints |
| --- | --- | --- | --- | --- |
| `years` | Years to compare | text | "10" |  |
| `homePrice` | Home price | text | "400000" |  |
| `downPayment` | Down payment | text | "80000" |  |
| `buyingCosts` | Buying costs | text | "12000" |  |
| `mortgageRate` | Mortgage rate (%) | text | "6.5" |  |
| `mortgageYears` | Mortgage term (years) | text | "30" |  |
| `homeGrowth` | Yearly home value change (%) | text | "3" |  |
| `propertyTaxRate` | Property tax (% of value per year) | text | "1.1" |  |
| `maintenanceRate` | Maintenance (% of value per year) | text | "1" |  |
| `otherOwnerCosts` | Other owner costs per year | text | "1800" |  |
| `ownerCostIncrease` | Yearly increase in other owner costs (%) | text | "3" |  |
| `sellingCostRate` | Selling costs (% of sale price) | text | "6" |  |
| `rent` | Monthly rent | text | "2200" |  |
| `rentGrowth` | Yearly rent change (%) | text | "3" |  |
| `investmentReturn` | Yearly return on invested savings (%) | text | "5" |  |
| `decimals` | Decimal places in amounts | select | "2" | Allowed: 2, 0, 1, 3, 4, 5, 6 |

### Browser-agent workflow

1. Open the human page in a browser that supports WebMCP.
2. Discover the interface exposed by that page; use its actual schema.
3. Select files on the page first when the tool requires files.
4. Call `run_current_tool` with valid input and settings.
5. Inspect the returned result or error and the displayed output. Retrieve files from the displayed download links.

Calls do not automatically copy or download results. Browser permissions still apply. Interface availability alone is not proof of successful execution.

### Planning specification

1 to 50 years, mortgage terms of 1 to 40 years at 0 to 30 percent, home value and rent changes from -50 to 50 percent a year, tax, maintenance and selling cost rates from 0 to 20 percent, investment returns from 0 to 50 percent a year compounded monthly and amounts up to 1000000000000 at 0 to 3 decimal places, 100000000000 at 4, 10000000000 at 5 and 1000000000 at 6, with every yearly value and total within 1000000000000000 minor currency units (10000000000000 at 2 decimal places). Calculated locally in your browser. Downloads are a JSON report and a CSV with one row per year.

This describes intended requirements. Use the implementation notes, interface schema and observed output to determine current support.

### Complete machine-readable capability record

```json
{
  "id": "rent-versus-buy-calculator",
  "category": "finance-tools",
  "built": true,
  "requirements": "1 to 50 years, mortgage terms of 1 to 40 years at 0 to 30 percent, home value and rent changes from -50 to 50 percent a year, tax, maintenance and selling cost rates from 0 to 20 percent, investment returns from 0 to 50 percent a year compounded monthly and amounts up to 1000000000000 at 0 to 3 decimal places, 100000000000 at 4, 10000000000 at 5 and 1000000000 at 6, with every yearly value and total within 1000000000000000 minor currency units (10000000000000 at 2 decimal places). Calculated locally in your browser. Downloads are a JSON report and a CSV with one row per year.",
  "implementation": {
    "fields": [
      {
        "key": "years",
        "label": "Years to compare",
        "value": "10",
        "type": "text",
        "maxLength": 10,
        "help": "Whole years from 1 to 50."
      },
      {
        "key": "homePrice",
        "label": "Home price",
        "value": "400000",
        "type": "text",
        "maxLength": 30,
        "help": "The purchase price."
      },
      {
        "key": "downPayment",
        "label": "Down payment",
        "value": "80000",
        "type": "text",
        "maxLength": 30,
        "help": "Cannot be more than the price."
      },
      {
        "key": "buyingCosts",
        "label": "Buying costs",
        "value": "12000",
        "type": "text",
        "maxLength": 30,
        "help": "Closing costs and other one-time costs paid when you buy."
      },
      {
        "key": "mortgageRate",
        "label": "Mortgage rate (%)",
        "value": "6.5",
        "type": "text",
        "maxLength": 20,
        "help": "From 0 to 30."
      },
      {
        "key": "mortgageYears",
        "label": "Mortgage term (years)",
        "value": "30",
        "type": "text",
        "maxLength": 10,
        "help": "Whole years from 1 to 40."
      },
      {
        "key": "homeGrowth",
        "label": "Yearly home value change (%)",
        "value": "3",
        "type": "text",
        "maxLength": 20,
        "help": "From -50 to 50."
      },
      {
        "key": "propertyTaxRate",
        "label": "Property tax (% of value per year)",
        "value": "1.1",
        "type": "text",
        "maxLength": 20,
        "help": "From 0 to 20, your own local rate."
      },
      {
        "key": "maintenanceRate",
        "label": "Maintenance (% of value per year)",
        "value": "1",
        "type": "text",
        "maxLength": 20,
        "help": "From 0 to 20."
      },
      {
        "key": "otherOwnerCosts",
        "label": "Other owner costs per year",
        "value": "1800",
        "type": "text",
        "maxLength": 30,
        "help": "Insurance, association dues and similar costs in the first year."
      },
      {
        "key": "ownerCostIncrease",
        "label": "Yearly increase in other owner costs (%)",
        "value": "3",
        "type": "text",
        "maxLength": 20,
        "help": "From 0 to 100."
      },
      {
        "key": "sellingCostRate",
        "label": "Selling costs (% of sale price)",
        "value": "6",
        "type": "text",
        "maxLength": 20,
        "help": "From 0 to 20."
      },
      {
        "key": "rent",
        "label": "Monthly rent",
        "value": "2200",
        "type": "text",
        "maxLength": 30,
        "help": "Rent for a comparable home in the first year."
      },
      {
        "key": "rentGrowth",
        "label": "Yearly rent change (%)",
        "value": "3",
        "type": "text",
        "maxLength": 20,
        "help": "From -50 to 50."
      },
      {
        "key": "investmentReturn",
        "label": "Yearly return on invested savings (%)",
        "value": "5",
        "type": "text",
        "maxLength": 20,
        "help": "From 0 to 50. Divided by 12 and compounded monthly on the down payment and buying costs a renter keeps."
      },
      {
        "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 1 to 50 years with amounts up to 1000000000000, or less at 4 to 6 decimal places.",
    "experience": {
      "automatic": false,
      "single": false,
      "inputMaxLength": 1000000,
      "inputMode": "text",
      "label": "Home, mortgage and rent 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"
  }
}
```

## Page guide

Compare the cost of buying a home with renting a similar one over the years you choose. See home equity, owner costs, rent, the investment growth a renter keeps and the year buying starts to cost less, all from your own assumptions.

How can we improve this tool?

Report a problem or share an idea.

Please leave out private information. Your message and the tool name go to our team via PostHog.

### How to use Rent versus buy calculator

1. Enter the number of years, the home price, the down payment and buying costs.
2. Enter the mortgage rate and term, the yearly home value change and the owner costs.
3. Enter the selling costs, the monthly rent, the yearly rent change and the return on invested savings.
4. Review the net cost of each option and the break-even year, then download the JSON report or the yearly CSV.

## Useful next steps

- [Mortgage payment](https://happytails.ai/en/finance-tools/mortgage-payment/) ([Markdown](https://happytails.ai/en/finance-tools/mortgage-payment.md))

- [Loan payment](https://happytails.ai/en/finance-tools/loan-payment/) ([Markdown](https://happytails.ai/en/finance-tools/loan-payment.md))

- [Compound interest](https://happytails.ai/en/finance-tools/compound-interest/) ([Markdown](https://happytails.ai/en/finance-tools/compound-interest.md))

## Method

The mortgage is a level monthly payment, the same formula as the spreadsheet PMT function (Microsoft Support, PMT function, checked 16 October 2026), with interest rounded to the cent each month. For each year the net cost of buying adds the down payment, buying costs, mortgage payments, property tax, maintenance and other owner costs, then subtracts what selling at the end of that year would return after selling costs and the mortgage balance, and adds the growth the down payment and buying costs would have earned if invested, with the yearly return divided by 12 and compounded monthly. The net cost of renting is the rent paid.

### Break-even year

Buying advantage is the net cost of renting minus the net cost of buying. The first break-even year is the first year it is zero or more, and the break-even year is the first year from which it stays zero or more until the end of the comparison.

### Assumptions and limits

Home value, rent and other owner costs change once a year, and property tax and maintenance use the home value at the start of each year. The investment return compounds monthly, so 5 percent a year grows a balance by about 5.12 percent in a year. Only the down payment and buying costs are treated as invested by a renter; monthly cost differences are not. Income tax effects such as mortgage interest deductions and tax on gains are not included, and the property tax rate is your own. This is a calculation from your own assumptions, not advice about whether to buy.