# Time Dilation Calculator API

> For the complete documentation index, see [llms.txt](/llms.txt).

Relativistic time dilation, Lorentz factor, clock rate, and optional length contraction at any sub-light speed.

Use this endpoint to add the tool to your app, site, workflow, or agent without rebuilding formulas, validation, examples, and docs.

- Slug: `time-dilation-calculator`
- Category: `science`
- Version: `2026-04-22`
- Credits per successful call: 1
- Starts on: free
- Max payload: 65536 bytes
- Privacy mode: `hash_only`
- Available on: free, starter, pro, business, scale
- Browser tool: https://miniwebtool.com/time-dilation-calculator/

## Endpoint

`POST https://api.miniwebtool.com/v1/tools/time-dilation-calculator/run`

## Request body

| Field | Type | Required | Description |
| --- | --- | --- | --- |
| `velocity` | `float` | no | Speed of the moving frame |
| `velocity_unit` | `str` | no | pct_c | frac_c | km_s | m_s | km_h | mph Choices: pct_c, frac_c, km_s, m_s, km_h, mph |
| `proper_time` | `float` | no | Time elapsed on the moving clock |
| `time_unit` | `str` | no | seconds | minutes | hours | days | weeks | years Choices: seconds, minutes, hours, days, weeks, years |
| `proper_length` | `float | None` | no | Optional rest length for contraction |
| `length_unit` | `str` | no | m | km | ft | mi Choices: m, km, ft, mi |

## Example request

```json
{
  "velocity": 90,
  "velocity_unit": "pct_c",
  "proper_time": 1,
  "time_unit": "years"
}
```

## cURL

```bash
curl -X POST https://api.miniwebtool.com/v1/tools/time-dilation-calculator/run \
  -H 'Authorization: Bearer mwt_live_YOUR_KEY' \
  -H 'Content-Type: application/json' \
  -d '{"velocity":90,"velocity_unit":"pct_c","proper_time":1,"time_unit":"years"}'
```

## Response envelope

```json
{
  "request_id": "01K...",
  "tool": "time-dilation-calculator",
  "tool_version": "2026-04-22",
  "credits_used": 1,
  "result": {}
}
```

## Errors

Errors are RFC 7807 `application/problem+json`. Branch on `code`, not `title`.

## MCP

Agents can discover and call this tool through `https://api.miniwebtool.com/mcp` or `https://api.miniwebtool.com/v1/mcp` using MCP `tools/list` and `tools/call`.

## Frequently asked

### What does the Time Dilation Calculator API do?

Relativistic time dilation, Lorentz factor, clock rate, and optional length contraction at any sub-light speed. Use it to add this utility without rebuilding formulas, validation, examples, and documentation.

### How much does one call cost?

1 credit per successful call. Failed calls do not bill.

### What parameters are required?

Required fields: (none). Full schema at `https://api.miniwebtool.com/v1/openapi.json`.

### Is this deterministic?

Yes. Same input, same output. Tool version: 2026-04-22.