# Rebar Calculator API

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

Rebar bar count, total linear footage, and weight for a concrete slab grid, sizes #3-#10 with cover and waste allowance.

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

- Slug: `rebar-calculator`
- Category: `construction`
- 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/rebar-calculator/

## Endpoint

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

## Request body

| Field | Type | Required | Description |
| --- | --- | --- | --- |
| `slab_length` | `float` | yes |  |
| `slab_width` | `float` | yes |  |
| `rebar_size` | `str` | no | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 Choices: 3, 4, 5, 6, 7, 8, 9, 10 |
| `unit_system` | `str` | no | imperial | metric Choices: imperial, metric |
| `spacing` | `float` | no |  |
| `cover` | `float` | no |  |
| `bar_length` | `float` | no |  |
| `direction` | `str` | no | both | length | width Choices: both, length, width |
| `waste_pct` | `float` | no |  |

## Example request

```json
{
  "slab_length": 20,
  "slab_width": 15,
  "rebar_size": "4",
  "unit_system": "imperial",
  "spacing": 12,
  "cover": 2
}
```

## cURL

```bash
curl -X POST https://api.miniwebtool.com/v1/tools/rebar-calculator/run \
  -H 'Authorization: Bearer mwt_live_YOUR_KEY' \
  -H 'Content-Type: application/json' \
  -d '{"slab_length":20,"slab_width":15,"rebar_size":"4","unit_system":"imperial","spacing":12,"cover":2}'
```

## Response envelope

```json
{
  "request_id": "01K...",
  "tool": "rebar-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 Rebar Calculator API do?

Rebar bar count, total linear footage, and weight for a concrete slab grid, sizes #3-#10 with cover and waste allowance. 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: slab_length, slab_width. Full schema at `https://api.miniwebtool.com/v1/openapi.json`.

### Is this deterministic?

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