> ## Documentation Index
> Fetch the complete documentation index at: https://dripart-claude-comfy-concurrency-limits-page-s84u33.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# StartLoop - ComfyUI Built-in Node Documentation

> The Start Loop node starts a looping structure inside a workflow.

The Start Loop node starts a looping structure inside a workflow. It runs the connected loop body one time per iteration and can count iterations in three ways: a fixed number of repetitions (simple), a numeric index range (For), or one pass per item in a list (List). Each pass exposes the current index, first/last flags, and an optional carried value that can be passed from one iteration to the next.

## Inputs

### Common Inputs

| Parameter | Description | Data Type | Required | Range |
| - | - | - | - | - |
| `mode` | The loop iteration mode (default: "simple"). The selected mode determines which additional parameters are shown. | DYNAMIC\_COMBO | Yes | `"simple"`<br />`"For"`<br />`"List"` |
| `cache_iterations` | Reuse unchanged iteration results from previous executions. Disable to execute every iteration again. Default: false. | BOOLEAN | Yes | true<br />false |
| `parent_iteration` | Connect iteration\_index from an outer Start Loop to nest this loop. This input is force-input only (a link is required). | INT | No | Any integer |
| `initial_iteration_value` | Value exposed as current\_iteration\_value on the first iteration. | ANY (type-matched) | No | Any value |

### Simple Mode Inputs

| Parameter | Description | Data Type | Required | Range |
| - | - | - | - | - |
| `num_iterations` | Number of times to execute the loop body. Default: 4. | INT | Yes | Minimum 0 |

### For Mode Inputs

| Parameter | Description | Data Type | Required | Range |
| - | - | - | - | - |
| `start_iteration_index` | Index of the first iteration when using For loop mode. Default: 0. | INT | Yes | Any integer |
| `max_iteration` | The exclusive stopping value for iteration\_index in For mode. Default: 4. | INT | Yes | Maximum 0xffffffffffffffff |
| `step` | The index step size between each iteration when using For loop mode. Default: 1. | INT | Yes | Minimum 1 |

### List Mode Inputs

| Parameter | Description | Data Type | Required | Range |
| - | - | - | - | - |
| `list` | List of items the loop iterates on. The loop body executes once per item. | ANY (type-matched list item) | Yes | Any list |

Notes:

* Only the parameters belonging to the currently selected `mode` are shown and used.
* In Simple mode, the iteration indices run from 0 up to `num_iterations` minus 1. In For mode, indices run from `start_iteration_index` up to (but not including) `max_iteration`, increasing by `step`. In List mode, one iteration runs per item in `list`.
* `step` must not be 0; a value of 0 raises an error. Values below 1 are not allowed.
* If the computed number of iterations is zero, the `is_last` output is reported as true and the loop body does not run.

## Outputs

| Output Name | Description | Data Type |
| - | - | - |
| `iteration_index` | Index of the current loop iteration. | INT |
| `is_first` | True during the first iteration of the loop. | BOOLEAN |
| `is_last` | True during the last iteration of the loop. | BOOLEAN |
| `list_item` | Current item from the list when using List mode. None in Simple and For modes. | ANY (type-matched) |
| `current_iteration_value` | Loop-carried value for the current iteration: initial\_iteration\_value on the first iteration, then next\_iteration\_value from End Loop on each subsequent iteration. | ANY (type-matched) |

> This documentation was AI-generated. If you find any errors or have suggestions for improvement, please feel free to contribute! [Edit on GitHub](https://github.com/Comfy-Org/embedded-docs/blob/main/comfyui_embedded_docs/docs/StartLoop/en.md)

***

**Source fingerprint (SHA-256):** `be34fedd4db9d4f4cc795855c87f6489f294e029da316b5dc66e5af7dff004a9`


This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.