January 20, 2025
The Hidden Cost of AWS Data Transfer
6 min read
Moving packets across regions or out to the internet is not free. AWS charges for every gigabyte transferred, and the fees vary depending on source, destination, and protocol.
The risk is especially high for teams that replicate data between environments or expose dashboards to clients without throttling. Data transfer can easily become the single largest line item if you're not tracking it.
Three things to monitor
- Cross-region traffic: Transfers between us-east-1 and eu-west-1 are billed per GB twice, even if you think you're just syncing backups.
- VPC endpoints: Data moved through Gateway or Interface endpoints counts toward the transfer quotas.
- CloudFront and egress: Public downloads incur higher rates unless routed through edge caches.
Sonar bookmarks these chargeable flows so you can set alerts before the cost sneaks into production.