AWS bill line item
USE1-USW2-AWS-Out-Bytes
You are being charged for data sent from one AWS region (here, us-east-1) to a different AWS region (here, us-west-2).
Inter-region data transfer
Verified against official AWS documentation last checked
Why it shows up
This appears whenever resources in different regions talk to each other: cross-region database replication or read replicas, multi-region S3 replication, a service in one region calling an API hosted in another, or disaster-recovery jobs.
It's confusing because AWS emits two line items for every transfer: a "{Source}-{Dest}-AWS-Out-Bytes" on the source side and a "{Dest}-{Source}-AWS-In-Bytes" on the destination side. Only the outbound side from the source region carries a charge; the inbound side is $0.
How to cut it
- Co-locate chatty services and their data stores in the same region wherever latency or compliance requirements allow.
- Use cross-region replication and read replicas deliberately (for DR/compliance), not as a default multi-region pattern, since every byte is billed on the sending side.
- For multi-region active-active architectures, weigh whether a global accelerator, private connectivity, or regional caching reduces total cross-region volume.
- Group by Usage type in Cost Explorer to see which region pair is generating the charge before optimizing.
How to read this code
USE1 / USE2us-east-1 (N. Virginia) / us-east-2 (Ohio)
USW1 / USW2us-west-1 (N. California) / us-west-2 (Oregon)
USE1-USW2- (a paired prefix)An inter-region transfer between the two named regions: the first is the source, the second is the destination. Only the source region's outbound leg is billed; the destination's inbound leg is $0.
-AWS-Out-Bytes / -AWS-In-BytesOutbound (billed) vs. inbound (free) data transfer between AWS regions, or between AWS and the public internet.
Source
Source: AWS docs →Found USE1-USW2-AWS-Out-Bytes on your own bill?
Drop your Cost Explorer CSV into the AWS Bill Analyzer. It'll flag line items like this one on your own bill and link straight back to the fix.
Analyze your own bill →The meter you don't watch still grows.
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