To make Deployments, the Vercel platform must first build a project. Building projects in the cloud is much faster than building locally, however, it is possible for builds to get queued when making multiple deployments at the same time.
By default, Vercel accounts have access to a single concurrent build slot. This means that only a single deployment can be building at any one time unless additional concurrent build slots are purchased. The maximum number of concurrent build slots is dependent on the account plan, this is shown below:
- Hobby (1)
- Pro (12)
- Enterprise (Custom)
It is not possible to increase the number of concurrent build slots available for Hobby accounts, if your project would benefit from additional build slots, you may wish to consider upgrading to a Pro team plan.
Additional concurrent build slots can be purchased for Pro team plans from the Vercel Dashboard. To do so, select the Pro team you wish to add the additional build slots to from the team picker in the header. Then, click "Settings" and select the "Billing" section.
From the "Billing" section, find the fieldset labelled "Concurrent Builds" and enter the total number of build slots required before clicking "Confirm". The fieldset is shown below:
Commits to a single git branch work slightly differently and aren't affected by how many concurrent builds your team has. When committing to a branch, only one commit on that branch can be built at a time, even if you have more concurrent builds purchased.
With each new push, if Vercel is already building a previous commit on the same branch, the current build will complete and any commit pushed during this time will be queued. Once the first build completes, the most recent commit will begin deployment and the other queued builds will be cancelled. This ensures that you always have the latest changes deployed as quickly as possible.