Why cloud egress is expensive

Cloud regions are buildings full of servers. Getting a bit onto a disk inside that building is an internal operation. Getting the same bit to a laptop on another continent is someone else’s network, plus peering, plus last-mile capacity. Public list prices put most of that cost on the sender as internet egress.

This is why a 50 GB object-store bill can sit next to a 2 TB download bill that is an order of magnitude larger. The storage SKU did not fail. The traffic path did.

CDN hit ratio is a lever, not a discount code

If 80% of bytes are served from a CDN cache at the edge, only 20% of origin egress is billed at the cloud’s internet rate. That is the model the SightLab egress calculator uses when you set a CDN hit ratio. It is not the same as a CloudFront or Cloudflare CDN SKU, which has its own request and regional data-transfer prices.

A cache that misses on every unique download (software artifacts, one-shot backups, personalized media) will not save you. A cache that hits on a public asset library will.

Cross-region is a different problem

Copying buckets or databases between regions is billed as cross-region data transfer, not as internet egress, unless you hairpin through a public endpoint. Replication for disaster recovery therefore has a standing monthly cost even when no user downloads anything. Put that number in the calculator as “cross region,” not “internet.”

Zero-egress products still have a model

Cloudflare documents $0 egress for R2 and Workers on the public internet. That does not make every workload free: storage, Class A/B operations, Workers CPU-ms, and the $5 Paid platform fee still apply. AWS, Azure, and GCP remain rational when the data never leaves the region, when credits cover the first year, or when the rest of the stack is already there.

The useful question is not “which cloud is cheapest.” It is “which destination am I actually paying for.”