# Bolt circle calculator

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

## Tool capabilities

| Property | Value |
| --- | --- |
| Tool ID | `bolt-circle-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

Generate up to 360 equally spaced hole centres. Zero degrees points right along +X; +Y points up. The SVG is a schematic, not a full-size drilling template. Hole diameter and engineering fit are not evaluated. 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 |
| --- | --- | --- | --- | --- |
| `diameter` | Bolt-circle diameter | number | 100 | min=0 max=1000000000 step=any |
| `unit` | Coordinate unit | select | "mm" | Allowed: mm, cm, m, in, ft |
| `holes` | Hole centres | number | 4 | min=1 max=360 step=1 |
| `startAngle` | First angle (degrees) | number | 0 | min=-360000 max=360000 step=any |
| `direction` | Numbering direction | select | "Counterclockwise" | Allowed: Counterclockwise, Clockwise |
| `centerX` | Centre X | number | 0 | min=-1000000 max=1000000 step=any |
| `centerY` | Centre Y | number | 0 | min=-1000000 max=1000000 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

1–360 equally spaced centres. Start angles can be −360,000 to 360,000 degrees and are normalized to 0–360 degrees. Extremely small circles relative to a large centre offset are rejected to avoid numeric precision loss.

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

### Complete machine-readable capability record

```json
{
  "id": "bolt-circle-calculator",
  "category": "calculators",
  "built": true,
  "requirements": "1–360 equally spaced centres. Start angles can be −360,000 to 360,000 degrees and are normalized to 0–360 degrees. Extremely small circles relative to a large centre offset are rejected to avoid numeric precision loss.",
  "implementation": {
    "fields": [
      {
        "key": "diameter",
        "label": "Bolt-circle diameter",
        "value": 100,
        "type": "number",
        "min": 0,
        "max": 1000000000,
        "step": "any"
      },
      {
        "key": "unit",
        "label": "Coordinate unit",
        "value": "mm",
        "type": "select",
        "values": [
          "mm",
          "cm",
          "m",
          "in",
          "ft"
        ]
      },
      {
        "key": "holes",
        "label": "Hole centres",
        "value": 4,
        "type": "number",
        "min": 1,
        "max": 360,
        "step": 1
      },
      {
        "key": "startAngle",
        "label": "First angle (degrees)",
        "value": 0,
        "type": "number",
        "min": -360000,
        "max": 360000,
        "step": "any"
      },
      {
        "key": "direction",
        "label": "Numbering direction",
        "value": "Counterclockwise",
        "type": "select",
        "values": [
          "Counterclockwise",
          "Clockwise"
        ]
      },
      {
        "key": "centerX",
        "label": "Centre X",
        "value": 0,
        "type": "number",
        "min": -1000000,
        "max": 1000000,
        "step": "any"
      },
      {
        "key": "centerY",
        "label": "Centre Y",
        "value": 0,
        "type": "number",
        "min": -1000000,
        "max": 1000000,
        "step": "any"
      }
    ],
    "input": false,
    "live": true,
    "presentation": "metrics",
    "note": "Generate up to 360 equally spaced hole centres. Zero degrees points right along +X; +Y points up. The SVG is a schematic, not a full-size drilling template. Hole diameter and engineering fit are not evaluated. 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

Generate equally spaced hole-centre coordinates from a circle diameter. Set the first angle, numbering direction and centre offset.

How can we improve this tool?

Report a problem or share an idea.

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### How to use Bolt circle calculator

1. Set circle diameter, unit and number of equally spaced centres.
2. Choose the first angle, direction and centre coordinates.
3. Review the diagram and download the full coordinate CSV or SVG.

## Useful next steps

- [Roof pitch calculator](https://happytails.ai/en/calculators/roof-pitch-calculator/) ([Markdown](https://happytails.ai/en/calculators/roof-pitch-calculator.md))

- [Circle](https://happytails.ai/en/calculators/circle/) ([Markdown](https://happytails.ai/en/calculators/circle.md))

- [Mm to inches](https://happytails.ai/en/unit-converters/mm-to-inches/) ([Markdown](https://happytails.ai/en/unit-converters/mm-to-inches.md))

## Set the circle and coordinate system

Enter the diameter of the circle passing through the hole centres. Zero degrees points right along positive X. Positive Y points up. Coordinates use the selected unit and are shifted by your entered centre X and Y values.

### Choose where numbering begins

The first angle sets hole 1. Counterclockwise order increases each angle; clockwise order decreases it. Spacing is 360 degrees divided by the number of centres. Four centres on a 100 mm diameter circle, starting at zero around the origin, are (50, 0), (0, 50), (−50, 0) and (0, −50) mm.

### Check the table and diagram together

The CSV contains every hole number, angle and coordinate in generated order. The SVG shows the same mathematical orientation. Markers represent centres only: their drawn size is not a hole diameter, and the schematic is not a full-size drilling template.

### Download the coordinate list

Save the CSV, SVG or calculation report locally. Hole size, edge distance, machining tolerances, fastener choice and strength are not evaluated. Check coordinate conventions against the equipment or drawing that will use the numbers.