# Time calculator

- Human page: https://happytails.ai/en/date-time-tools/time-calculator/
- Markdown: https://happytails.ai/en/date-time-tools/time-calculator.md
- Structured JSON: https://happytails.ai/agents/en/date-time-tools/time-calculator/index.json
- Visibility: public

## Tool capabilities

| Property | Value |
| --- | --- |
| Tool ID | `time-calculator` |
| Category | date-time-tools |
| 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 | /api/v1/tools/time-calculator/run |
| Browser-agent interface | run_current_tool |

### Inputs and settings

Text input: Your text.

Example or placeholder shown in the interface (not a validated fixture):

```text
Hello world!
```

Change the input or settings to update your result. Results update as you type. Up to 1,000,000 characters.

| Setting | Meaning | Control type | Default | Constraints |
| --- | --- | --- | --- | --- |
| `start` | Start time | text | "09:00" |  |
| `end` | End time | text | "17:00" |  |
| `break` | Unpaid break (minutes) | number | 30 |  |
| `overnight` | Ends next day | checkbox | false |  |
| `rate` | Hourly rate | number | 20 |  |

### HTTP contract

API calls process supplied data on the server. The website origin is `https://happytails.ai`. Server API hosting is not connected on the public website yet. Use your local server origin to test these requests.

```http
POST https://happytails.ai/api/v1/tools/time-calculator/run
Content-Type: application/json
```

[Detailed operation reference](https://happytails.ai/en/api/tools/time-calculator.md) · [Shared API guide](https://happytails.ai/en/api.md)

#### Limits

| Limit | Value |
| --- | --- |
| request_bytes | 8388608 |
| input_characters | 1000000 |
| files_bytes | 5242880 |
| max_files | 0 |
| timeout_seconds | 12 |

#### Complete input schema

```json
{
  "type": "object",
  "additionalProperties": false,
  "properties": {
    "input": {
      "type": "string",
      "maxLength": 1000000,
      "default": "",
      "description": "Plain text input. File tools use files instead unless otherwise documented."
    },
    "options": {
      "type": "object",
      "additionalProperties": false,
      "properties": {
        "start": {
          "type": "string",
          "description": "Start time",
          "default": "09:00"
        },
        "end": {
          "type": "string",
          "description": "End time",
          "default": "17:00"
        },
        "break": {
          "type": "number",
          "description": "Unpaid break (minutes)",
          "default": 30.0
        },
        "overnight": {
          "type": "boolean",
          "description": "Ends next day",
          "default": false
        },
        "rate": {
          "type": "number",
          "description": "Hourly rate",
          "default": 20.0
        }
      }
    }
  }
}
```

#### Complete output schema

```json
{
  "type": "object",
  "required": [
    "tool",
    "result"
  ],
  "properties": {
    "tool": {
      "type": "string"
    },
    "result": {
      "type": "object",
      "required": [
        "text",
        "files"
      ],
      "properties": {
        "text": {
          "type": [
            "string",
            "null"
          ]
        },
        "data": {
          "description": "Parsed JSON when the textual result is JSON."
        },
        "name": {
          "type": "string"
        },
        "mime": {
          "type": "string"
        },
        "files": {
          "type": "array",
          "items": {
            "type": "object",
            "required": [
              "name",
              "mime",
              "bytes",
              "base64"
            ],
            "properties": {
              "name": {
                "type": "string"
              },
              "mime": {
                "type": "string"
              },
              "bytes": {
                "type": "integer"
              },
              "base64": {
                "type": "string",
                "contentEncoding": "base64"
              }
            }
          }
        }
      }
    }
  }
}
```

#### Error and retry handling

Failures return a non-200 status and `error.code` plus `error.message`. Correct invalid input before retrying; retry server-busy responses with bounded backoff. Returned files contain Base64 data, not persistent download URLs. Decode and inspect the output before treating conversion as successful. See the shared API guide for the complete status and timeout rules.

### 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

Add/subtract hours/minutes/seconds and convert decimal hours.

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

### Complete machine-readable capability record

```json
{
  "id": "time-calculator",
  "category": "date-time-tools",
  "built": true,
  "requirements": "Add/subtract hours/minutes/seconds and convert decimal hours.",
  "implementation": {
    "fields": [
      {
        "key": "start",
        "label": "Start time",
        "value": "09:00",
        "type": "text"
      },
      {
        "key": "end",
        "label": "End time",
        "value": "17:00",
        "type": "text"
      },
      {
        "key": "break",
        "label": "Unpaid break (minutes)",
        "value": 30,
        "type": "number"
      },
      {
        "key": "overnight",
        "label": "Ends next day",
        "value": false,
        "type": "checkbox"
      },
      {
        "key": "rate",
        "label": "Hourly rate",
        "value": 20,
        "type": "number"
      }
    ],
    "experience": {
      "automatic": true,
      "single": false,
      "label": "Your text",
      "placeholder": "Hello world!",
      "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": "POST /api/v1/tools/time-calculator/run",
  "api": {
    "id": "time-calculator",
    "name": "Time calculator",
    "category": "date-time-tools",
    "description": "Add/subtract hours/minutes/seconds and convert decimal hours.",
    "notes": "",
    "human_path": "/en/date-time-tools/time-calculator/",
    "method": "POST",
    "endpoint": "/api/v1/tools/time-calculator/run",
    "schema_url": "/api/v1/tools/time-calculator",
    "input_schema": {
      "type": "object",
      "additionalProperties": false,
      "properties": {
        "input": {
          "type": "string",
          "maxLength": 1000000,
          "default": "",
          "description": "Plain text input. File tools use files instead unless otherwise documented."
        },
        "options": {
          "type": "object",
          "additionalProperties": false,
          "properties": {
            "start": {
              "type": "string",
              "description": "Start time",
              "default": "09:00"
            },
            "end": {
              "type": "string",
              "description": "End time",
              "default": "17:00"
            },
            "break": {
              "type": "number",
              "description": "Unpaid break (minutes)",
              "default": 30.0
            },
            "overnight": {
              "type": "boolean",
              "description": "Ends next day",
              "default": false
            },
            "rate": {
              "type": "number",
              "description": "Hourly rate",
              "default": 20.0
            }
          }
        }
      }
    },
    "output_schema": {
      "type": "object",
      "required": [
        "tool",
        "result"
      ],
      "properties": {
        "tool": {
          "type": "string"
        },
        "result": {
          "type": "object",
          "required": [
            "text",
            "files"
          ],
          "properties": {
            "text": {
              "type": [
                "string",
                "null"
              ]
            },
            "data": {
              "description": "Parsed JSON when the textual result is JSON."
            },
            "name": {
              "type": "string"
            },
            "mime": {
              "type": "string"
            },
            "files": {
              "type": "array",
              "items": {
                "type": "object",
                "required": [
                  "name",
                  "mime",
                  "bytes",
                  "base64"
                ],
                "properties": {
                  "name": {
                    "type": "string"
                  },
                  "mime": {
                    "type": "string"
                  },
                  "bytes": {
                    "type": "integer"
                  },
                  "base64": {
                    "type": "string",
                    "contentEncoding": "base64"
                  }
                }
              }
            }
          }
        }
      }
    },
    "processing": "Server; same transformation code as browser tools",
    "limits": {
      "request_bytes": 8388608,
      "input_characters": 1000000,
      "files_bytes": 5242880,
      "max_files": 0,
      "timeout_seconds": 12
    }
  },
  "agent_processing": "Server; same transformation code as browser tools",
  "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

Add/subtract hours/minutes/seconds and convert decimal hours..

## How to use Time calculator

1. Enter your text in the input field.
2. The result updates as you type. Adjust the available settings if needed.
3. Review the result, then use Copy result or a download link when available.

## Working with time calculator

Date calculations can depend on calendar rules, time zones and whether endpoints are included. A duration in hours is different from a number of calendar days when daylight-saving changes occur.

## Common questions

### Are all days exactly 24 hours long?

Elapsed time across a daylight-saving transition can differ from a simple calendar-day count. Use the measure relevant to your schedule.

### Why can the same timestamp show different dates?

A timestamp represents an instant, while a calendar date is interpreted in a time zone. Near midnight, the same instant can fall on different local dates.

## Useful next steps

- [Meeting cost](https://happytails.ai/en/business-tools/meeting-cost/): Estimate a meeting’s total staff cost. ([Markdown](https://happytails.ai/en/business-tools/meeting-cost.md))

- [Hourly to salary](https://happytails.ai/en/business-tools/hourly-to-salary/): Estimate annual and monthly gross pay from an hourly rate. ([Markdown](https://happytails.ai/en/business-tools/hourly-to-salary.md))