> ## Documentation Index
> Fetch the complete documentation index at: https://heygen-1fa696a7.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.
# Burst Concurrency
> Run above your included concurrency on demand. Enterprise workspaces opt in to burst, set an extra cap of up to 50 workflows, and pay 1.5× the contract rate only on the jobs that run above the included slots.
Burst is available on **Enterprise** plans. It is enabled per workspace by your account team; [contact sales](https://www.heygen.com/contact-us/sales) to turn it on.
Every Enterprise workspace includes a fixed number of concurrent workflow slots (20 by default). Burst lets the workspace run **above** that number when a batch lands, without buying a higher permanent cap. You set one extra cap for the workspace, and it applies to each burst-eligible workflow type separately: with a +30 cap, up to 30 extra avatar renders **and** up to 30 extra video translations can run at the same time. Only the workflows that actually run above the included slots are billed at the burst rate. Burst is shared across the web app and the API.
## Turn on burst
1. Open [Usage](https://app.heygen.com/developers/usage) in the API dashboard. Under **Capacity**, the **Concurrency** tile shows your included slots.
2. Click **Set up burst**, choose the extra cap (**+5 to +50** workflows), and accept the rate notice.
3. Save. The tile now reads `20 + 30` with a **Burst** chip, and **Manage burst** lets you change the cap or turn burst off at any time.
Workspace admins can also see included and burst capacity under **Settings → Usage & History**.
## How burst is billed
| | Included slots | Burst slots |
| :----------------- | :----------------- | :------------------------------------------------------------------------------------------------------------------------------------- |
| Rate | Your contract rate | **1.5×** your contract rate |
| Example, Avatar IV | 0.1 credits / sec | 0.15 credits / sec |
| Applies to | All workflows | [HeyGen Video](/reference/create-video) renders and [video translations](/docs/video-translate), each with its own pool of extra slots |
A workflow takes a slot when it is admitted and holds it until it completes. If every included slot for its type is busy at admission, the workflow runs in a burst slot and its whole render is billed at the burst rate: the duration is billed to the second as usual, then the 1.5× is applied and rounded up to the next whole quota unit. Workflows admitted into an included slot bill at the normal rate even while others are bursting. You only pay the premium for workflows that actually burst.
Burst covers full avatar renders and video translations. Segment renders and free regenerations run in the included slots at the normal rate, and [Video Agent](/docs/video-agent) sessions keep their own concurrency limit.
## See what burst cost you
Every burst workflow is tagged **Burst** in the [Activity tab](https://app.heygen.com/developers/usage?tab=activity), next to its credits. While burst is on, the Usage sidebar shows a **Burst** panel with the premium credits and the number of burst workflows for the selected period.
## API behavior
With burst on, [`POST /v3/videos`](/reference/create-video) and [`POST /v3/video-translations`](/reference/create-video-translation) each accept requests up to *included + extra* concurrent workflows of their own type, so a +30 cap allows up to 50 avatar renders and up to 50 translations at once. Requests beyond that total return `429 Too Many Requests` with a `Retry-After` header, the same as any [concurrency limit](/docs/usage-limits#concurrency-limits). Batch endpoints such as [`POST /v3/videos/batch`](/reference/create-video-batch) queue their items through the same slots.