Connect to a Cluster

Atlas provides instructions on connecting to a cluster via the mongo shell, a MongoDB driver, or MongoDB Compass via the Atlas UI.

Connection Limits and Instance Sizes

Atlas sets the limits for concurrent incoming connections based on instance size:

Instance Size Maximum Number of Concurrent Incoming Connections
M0 100
M10 350
M20 700
M30 2000
M40 4000
M50 6000
M60 8000
M80 ( GCP only) 16000
M90 ( Azure only) 10000
M100 16000



Clients must have support for TLS/SSL to connect to an Atlas cluster.

Clients must have support for the SNI TLS extension to connect to an Atlas M0 Free Tier cluster.

To access a cluster, you must connect from an IP address on the Atlas project’s IP whitelist. If you need to add an IP address to the whitelist, you can do so in the Connect dialog. You can also add the IP address from the Security tab.

Connect to Your Cluster


Open the Connect dialog.

Go to the Clusters view. Click the Connect button for the cluster to which you wish to connect.


From the Connect dialog, review the IP Whitelist.

Atlas only allows client connections to the cluster from entries in the project’s whitelist.

Atlas displays any entries already on the project whitelist in the Connect modal under Check the IP Whitelist. If you do not see the IP address of your client on the list, you can:

  • Click Add Entry to add a single IP address or a CIDR-notated range of addresses.

    For Atlas clusters deployed on Amazon Web Services and using VPC Peering, you can add a Security Group associated with the peer VPC.

  • Click Add Current IP Address to add your current IP address.

  • Click Allow Access From Anywhere to allow access from any IP address.


    Using Allow Access From Anywhere results in all clusters in the Atlas project being publically accessible. Consider the security risks of having public-facing MongoDB clusters before using this option.


Select your preferred connection method.

For Choose a connection method, Atlas provides instructions for each listed connection method. Click your preferred connection method and follow the instructions given.