# Lens Equation Calculator API

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

Thin-lens equation solver for image distance, focal length, or object distance with magnification and image properties.

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

- Slug: `lens-equation-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/lens-equation-calculator/

## Endpoint

`POST https://api.miniwebtool.com/v1/tools/lens-equation-calculator/run`

## Request body

| Field | Type | Required | Description |
| --- | --- | --- | --- |
| `solve_for` | `str` | no | image_distance | focal_length | object_distance Choices: image_distance, focal_length, object_distance |
| `lens_type` | `str` | no | converging | diverging Choices: converging, diverging |
| `unit` | `str` | no | mm | cm | m Choices: mm, cm, m |
| `focal_length` | `float | None` | no | Focal length f (positive converging, negative diverging) |
| `object_distance` | `float | None` | no | Object distance do |
| `image_distance` | `float | None` | no | Image distance di (negative = virtual) |
| `object_height` | `float | None` | no | Optional object height for image size |

## Example request

```json
{
  "solve_for": "image_distance",
  "lens_type": "converging",
  "unit": "cm",
  "focal_length": 10,
  "object_distance": 30
}
```

## cURL

```bash
curl -X POST https://api.miniwebtool.com/v1/tools/lens-equation-calculator/run \
  -H 'Authorization: Bearer mwt_live_YOUR_KEY' \
  -H 'Content-Type: application/json' \
  -d '{"solve_for":"image_distance","lens_type":"converging","unit":"cm","focal_length":10,"object_distance":30}'
```

## Response envelope

```json
{
  "request_id": "01K...",
  "tool": "lens-equation-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 Lens Equation Calculator API do?

Thin-lens equation solver for image distance, focal length, or object distance with magnification and image properties. 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.