# Roof pitch calculator

- Human page: https://happytails.ai/en/calculators/roof-pitch-calculator/
- Markdown: https://happytails.ai/en/calculators/roof-pitch-calculator.md
- Structured JSON: https://happytails.ai/agents/en/calculators/roof-pitch-calculator/index.json
- Visibility: public

## Tool capabilities

| Property | Value |
| --- | --- |
| Tool ID | `roof-pitch-calculator` |
| Category | calculators |
| Implementation | Registered implementation. Registration alone is not a production-quality guarantee. |
| Browser execution | Automatic updates after valid input or file selection. |
| Browser processing | Browser; see tool notes for network behavior. |
| HTTP API | Not callable through HTTP. |
| Browser-agent interface | run_current_tool |

### Implementation notes

Convert rise/run, pitch per 12 and slope angle. Slopes from 0 to 89.9 degrees are supported. The calculated slope length excludes overhang details and cuts. Changing units keeps the entered numbers. All calculations stay on your device. These estimates do not establish structural safety or code compliance.

### Inputs and settings

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

| Setting | Meaning | Control type | Default | Constraints |
| --- | --- | --- | --- | --- |
| `mode` | Known values | select | "Rise and run" | Allowed: Rise and run, Pitch per 12, Angle |
| `run` | Horizontal run | number | 4 | min=0 max=1000000000 step=any |
| `runUnit` | Run unit | select | "m" | Allowed: mm, cm, m, in, ft |
| `rise` | Vertical rise | number | 3 | min=0 max=1000000000 step=any |
| `riseUnit` | Rise unit | select | "m" | Allowed: mm, cm, m, in, ft |
| `pitch` | Rise per 12 units of run | number | 9 | min=0 max=10000 step=any |
| `angle` | Slope angle (degrees) | number | 36.86989764584402 | min=0 max=89.9 step=any |

### 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

Nonnegative slopes from 0 to 89.9 degrees. One straight roof plane; vertical roofs and negative slopes are outside this calculator. This is geometry, not a material or building-code approval.

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

### Complete machine-readable capability record

```json
{
  "id": "roof-pitch-calculator",
  "category": "calculators",
  "built": true,
  "requirements": "Nonnegative slopes from 0 to 89.9 degrees. One straight roof plane; vertical roofs and negative slopes are outside this calculator. This is geometry, not a material or building-code approval.",
  "implementation": {
    "fields": [
      {
        "key": "mode",
        "label": "Known values",
        "value": "Rise and run",
        "type": "select",
        "values": [
          "Rise and run",
          "Pitch per 12",
          "Angle"
        ]
      },
      {
        "key": "run",
        "label": "Horizontal run",
        "value": 4,
        "type": "number",
        "min": 0,
        "max": 1000000000,
        "step": "any",
        "help": "One roof plane, not the full roof span."
      },
      {
        "key": "runUnit",
        "label": "Run unit",
        "value": "m",
        "type": "select",
        "values": [
          "mm",
          "cm",
          "m",
          "in",
          "ft"
        ]
      },
      {
        "key": "rise",
        "label": "Vertical rise",
        "value": 3,
        "type": "number",
        "min": 0,
        "max": 1000000000,
        "step": "any",
        "showWhen": {
          "mode": [
            "Rise and run"
          ]
        }
      },
      {
        "key": "riseUnit",
        "label": "Rise unit",
        "value": "m",
        "type": "select",
        "values": [
          "mm",
          "cm",
          "m",
          "in",
          "ft"
        ],
        "showWhen": {
          "mode": [
            "Rise and run"
          ]
        }
      },
      {
        "key": "pitch",
        "label": "Rise per 12 units of run",
        "value": 9,
        "type": "number",
        "min": 0,
        "max": 10000,
        "step": "any",
        "showWhen": {
          "mode": [
            "Pitch per 12"
          ]
        }
      },
      {
        "key": "angle",
        "label": "Slope angle (degrees)",
        "value": 36.86989764584402,
        "type": "number",
        "min": 0,
        "max": 89.9,
        "step": "any",
        "showWhen": {
          "mode": [
            "Angle"
          ]
        }
      }
    ],
    "input": false,
    "live": true,
    "presentation": "metrics",
    "note": "Convert rise/run, pitch per 12 and slope angle. Slopes from 0 to 89.9 degrees are supported. The calculated slope length excludes overhang details and cuts. Changing units keeps the entered numbers. All calculations stay on your device. These estimates do not establish structural safety or code compliance.",
    "experience": {
      "automatic": true,
      "single": false,
      "inputMaxLength": 1000000,
      "inputMode": "text",
      "label": "Your text",
      "placeholder": "Type or paste your input…",
      "help": "Change the input or settings to update your result. Results update as you type. Up to 1,000,000 characters.",
      "action": null
    },
    "mode": "automatic",
    "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

Convert roof rise and run into pitch, angle and slope length. Start with measurements, a pitch per 12 or an angle.

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 Roof pitch calculator

1. Choose rise/run, pitch per 12 or angle as your input.
2. Enter the horizontal run and its unit.
3. Compare pitch, slope length and angle, then download the conversion.

## Useful next steps

- [Area](https://happytails.ai/en/unit-converters/area/) ([Markdown](https://happytails.ai/en/unit-converters/area.md))

- [Paint calculator](https://happytails.ai/en/calculators/paint-calculator/) ([Markdown](https://happytails.ai/en/calculators/paint-calculator.md))

- [Scientific calculator](https://happytails.ai/en/calculators/scientific-calculator/) ([Markdown](https://happytails.ai/en/calculators/scientific-calculator.md))

## Use horizontal run

Run is the horizontal distance for one roof plane. It is not the length along the slope. For a symmetric roof it is typically half the horizontal span, before separately accounting for overhang. Enter run in every mode so the result can also show rise and slope length.

### Convert the measurement you have

Choose Rise and run, Pitch per 12 or Angle. Pitch per 12 means vertical rise for every 12 units of horizontal run. A 3 metre rise over a 4 metre run is 9-in-12, a 75% slope and an angle of about 36.87 degrees. Its straight slope length is 5 metres.

### Read the area multiplier

For a uniform planar slope, the multiplier is slope length divided by horizontal run. Multiplying the horizontal plan area by that value gives the corresponding sloped area. Roof intersections, openings and overhangs still need their own measurements.

### Keep geometry separate from design

Download CSV, text or JSON calculations. The result does not select a roof material, establish a minimum permitted slope or size a structural rafter. Cuts, ridge deductions and construction details are excluded.