# Reynolds Number Calculator API

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

Reynolds number with laminar/transitional/turbulent classification using geometry-specific thresholds for pipes, plates, and channels.

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

- Slug: `reynolds-number-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/reynolds-number-calculator/

## Endpoint

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

## Request body

| Field | Type | Required | Description |
| --- | --- | --- | --- |
| `flow_type` | `str` | no | pipe | plate | channel Choices: pipe, plate, channel |
| `visc_mode` | `str` | no | dynamic | kinematic Choices: dynamic, kinematic |
| `velocity` | `float` | no |  |
| `velocity_unit` | `str` | no | m_s | cm_s | km_h | ft_s | mph | knot Choices: m_s, cm_s, km_h, ft_s, mph, knot |
| `length` | `float` | no | Characteristic length for the chosen geometry |
| `length_unit` | `str` | no | m | cm | mm | ft | in Choices: m, cm, mm, ft, in |
| `density` | `float | None` | no | Fluid density (visc_mode=dynamic) |
| `density_unit` | `str` | no | kg_m3 | g_cm3 | lb_ft3 Choices: kg_m3, g_cm3, lb_ft3 |
| `dynamic_viscosity` | `float | None` | no | Dynamic viscosity (visc_mode=dynamic) |
| `dynamic_viscosity_unit` | `str` | no | pa_s | mpa_s | cp | poise Choices: pa_s, mpa_s, cp, poise |
| `kinematic_viscosity` | `float | None` | no | Kinematic viscosity (visc_mode=kinematic) |
| `kinematic_viscosity_unit` | `str` | no | m2_s | mm2_s | cst | stokes Choices: m2_s, mm2_s, cst, stokes |

## Example request

```json
{
  "flow_type": "pipe",
  "velocity": 1,
  "length": 50,
  "length_unit": "mm",
  "density": 998,
  "dynamic_viscosity": 1,
  "dynamic_viscosity_unit": "cp"
}
```

## cURL

```bash
curl -X POST https://api.miniwebtool.com/v1/tools/reynolds-number-calculator/run \
  -H 'Authorization: Bearer mwt_live_YOUR_KEY' \
  -H 'Content-Type: application/json' \
  -d '{"flow_type":"pipe","velocity":1,"length":50,"length_unit":"mm","density":998,"dynamic_viscosity":1,"dynamic_viscosity_unit":"cp"}'
```

## Response envelope

```json
{
  "request_id": "01K...",
  "tool": "reynolds-number-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 Reynolds Number Calculator API do?

Reynolds number with laminar/transitional/turbulent classification using geometry-specific thresholds for pipes, plates, and channels. 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.