Egress (data transfer out)
Also called data transfer out, bandwidth out.
Data that leaves a cloud provider's network, such as files sent to users, which many providers bill per gigabyte.
Last updated
What it is.
Data coming into a cloud (ingress) is usually free. Data going out to the internet, to another region or sometimes to another zone often has a per-gigabyte price. Video, images, downloads, API responses and backups copied elsewhere all count.
Pricing differs a lot between providers and services. Some CDNs and storage services charge little or nothing for egress, while some clouds charge more for traffic between regions than within one.
Why it matters
Egress grows with success: more users and more media mean more data out. It is easy to miss in early estimates and can become one of the larger lines in a cloud bill. It also makes moving away from a provider expensive, which adds to lock-in.
In a product build
We estimate egress in the hosting plan from expected users and file sizes, put a CDN in front of anything large, keep services that talk a lot in the same region, and tag traffic so the bill shows which feature drives it.
Common mistakes.
- 01
Leaving egress out of the cost estimate altogether.
- 02
Splitting chatty services across regions or clouds.
- 03
Serving full-size images and video to every device.
Related terms.
- CDN (content delivery network)A network of servers around the world that keeps copies of your files close to users, so pages and media load faster.
- Object storageA way of storing files as objects in buckets, each with an ID and metadata, reached over HTTP and built to scale to huge amounts of data cheaply.
- Edge functionA small piece of server code that runs on a CDN's servers around the world, close to the user, instead of in one central region.
- Total cost of ownership (TCO)Everything a piece of software costs over its life, not just the price to build or buy it.
- IaaS (infrastructure as a service)Renting raw computing, storage and networking from a cloud provider, while you manage everything that runs on it.
Guides and pages
Browse the full glossary or read answers to common questions.
