All terms

Glossary

Egress cost

Also: Data transfer out

Charges for data leaving an AWS region, an availability zone or the cloud. Inbound data is usually free.

The price list is granular: within a zone, across zones, across regions, out to the internet. Spread an application across zones and you pay for every conversation between its parts.

This hits chatty architectures hardest: many small calls between services, logs shipped to another region, backups across region boundaries.

How you notice it

  • The bill grows while user numbers stay flat.
  • Data transfer accounts for more than ten percent of the monthly bill.
  • Services are spread across zones and talk to each other constantly.

Frequently asked

Is data transfer within a region free?

No. Within an availability zone it is free, across zone boundaries it is charged in both directions. That is exactly what hits architectures spread across three zones for resilience which make many small calls between their parts.

Read moreHidden architecture costs on AWS