Atlas Limitations

Atlas limits how many of each kind of component you can create, and the number of connections allowed to a cluster based on cluster tier. These tables outline component and connection limits.

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If any of these limits present a problem for your organization, please contact Atlas support.

Shards in Multi-Region Clusters12
Shards in Single-region clusters50
Total Nodes per Region of a Multi-Region Cluster40
Electable Nodes per Region7
Config Server Tier (minimum and maximum)M30

Atlas sets the limits for concurrent incoming connections based on the cluster tier and class:

Cluster TierMaximum Connections
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Atlas reserves a small portion of connections to each Atlas cluster for supporting Atlas services. Contact Atlas support for more information on Atlas reserved connections.

While there is no hard limit on the number of collections in a single cluster, the performance of a cluster might degrade if it serves a large number of collections and indexes. Larger collections have a greater impact on performance.

The recommended maximum combined number of collections and indexes by Atlas cluster tier are as follows:

Cluster tierRecommended maximum
M105,000 collections and indexes
M20 / M3010,000 collections and indexes
M40+100,000 collections and indexes
Total Network Peering Connections per Atlas Project


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Atlas limits the number of nodes per Network Peering connection based on the CIDR block and the region selected for the project.

Pending Network Peering Connections per Atlas Project25
Database Users per Atlas Project100
Atlas Users per Atlas Project500
Atlas Users per Atlas Organization500
API Keys per Atlas Organization500
Access List Entries per Atlas Project200
Users per Atlas Team250
Teams per Atlas Project100
Teams per Atlas Organization250
Teams per Atlas User100
Organizations per Atlas User250
Clusters per Atlas Project25
Projects per Atlas Organization250
Custom MongoDB roles per Atlas Project100
Assigned Roles per Database User100
Hourly Billing per Atlas Project


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A Technical Account Manager or Billing Admin can raise this limit.

Data Lake Tenants per Atlas User25

Atlas also limits how long particular labels of components can be.

ComponentCharacter Length Limit
Cluster Name


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Atlas truncates the cluster name to 23 characters in its internal interactions. In practice, this means:

  • Cluster names shorter than 23 characters can't end with hyphen or dash (-)
  • Cluster names 23 characters or longer can't use a hyphen or dash (-) as its 23rd character.
  • The first 23 characters in a cluster name must be unique within a project.
API Key Description250
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