Geographic Latency

Modal’s worker cluster is multi-cloud and multi-region. The vast majority of workers are located in the continental USA, but we do run workers in Europe and Asia.

Modal’s control plane is hosted in Virginia, USA (us-east-1).

Any time data needs to travel between the Modal client, our control plane servers, and our workers latency will be incurred. provides good estimates on the significance of the latency between regions. For example, the roundtrip latency between AWS us-east-1 (Virginia, USA) and us-west-1 (California, USA) is around 60ms.

You can observe the location identifier of a container via an environment variable. Logging this environment variable alongside latency information can reveal when geography is impacting your application performance.

Region selection

In cases where low-latency communication is required between your container and a network dependency (e.g a database), it is useful to ensure that Modal schedules your container in only regions geographically proximate to that dependency. For example, if you have an AWS RDS database in Virginia, USA (us-east-1), ensuring your Modal containers are also scheduled in Virginia means that network latency between the container and the database will be less than 5 milliseconds.

For more information, please see Region selection.