railway scale
Scale a service by setting the number of replicas in one or more regions.
The railway scale command applies replica changes through the same environment
patch flow that the dashboard uses, then commits the patch as a single change.
You can pass replica counts as positional arguments, run the interactive scale
TUI in a terminal, or drive scaling from agents and scripts.
Usage
You can also call the command as railway service scale. Both forms accept the
same arguments and behave identically.
Arguments
| Argument | Description |
|---|---|
REGION=REPLICAS | One or more replica assignments. REGION is a friendly region name (eu-west, us-east, us-west, southeast-asia) or a Railway region ID. REPLICAS is a non-negative integer. |
A maximum of 50 total replicas is supported across all regions.
Options
| Flag | Description |
|---|---|
-s, --service <SERVICE> | Service to scale. Defaults to the linked service. |
-e, --environment <ENV> | Environment the service is in. Defaults to the linked environment. |
--json | Output in JSON format. |
Examples
Run the interactive TUI
When run in a terminal with no replica assignments, railway scale opens an
interactive TUI for selecting regions and replica counts. Apply the changes
from the TUI to commit them.
Scale a service in one region
Scale across multiple regions
Scale a specific service in a specific environment
Remove replicas from a region
Setting a region to 0 removes all replicas from that region.
Output the result as JSON
Behavior
railway scale commits a single environment patch that updates the service's
multi-region replica configuration. The change is applied without a separate
redeploy step.
If you call railway scale non-interactively without any REGION=REPLICAS
arguments, the command exits with an error. Pass at least one assignment, or
run the command in a terminal to use the TUI.