Cloud egress cost explained

Egress is data leaving a cloud region toward a destination you pay for. The destination is usually the public internet. It can also be another region, another availability zone, or another cloud. Storing an object is cheap. Sending that object to a user, a CI runner, or a second region is where many bills jump.

SightLab Cost treats egress as its own calculator because the unit, the free allowance, and the destination type change the result more than the storage class does.

Three destination types that matter

Most public list prices split outbound traffic into at least three buckets:

• Internet: traffic that leaves the provider toward the public network. This is usually the most expensive path.
• Same region: traffic that stays inside one region. Often free or priced far below internet transfer, with exceptions for public IPs and NAT gateways.
• Cross region: traffic that leaves one region for another region of the same cloud. Priced between same-region and internet, and sensitive to the pair of regions.

How the bill is actually computed

Providers publish a free allowance, then a ladder of USD-per-GB tiers. A typical AWS internet path from us-east-1 starts with 100 GB free per month, then about $0.09/GB for the next 10 TB. Azure Bandwidth from East US currently starts near $0.08/GB after its own free grant. Google Cloud bills internet Data Transfer Out by source and destination geography. Cloudflare documents $0 egress for R2 and for Workers responses on the public network.

SightLab walks the published tiers after subtracting the free allowance (on by default) and, for internet traffic, after applying an optional CDN hit ratio. Decimal GB (10^9 bytes) is used, not GiB.

What this page is not

It is not a claim that one cloud is cheaper in every topology. Private interconnects, CloudFront, Cloud CDN, and committed-use discounts change the invoice. Use the egress calculator with your region and destination, then read the formula and sources under the result.