Network Inter Region Egress
This is traffic between two Google Cloud regions — it never leaves Google, but it is still billed. The rate depends on the specific pair of regions, and intercontinental pairs cost several times what neighbouring ones do. It is the usual hidden cost of a multi-region architecture.
Billed: Per gibibyte moved between two Google Cloud regions, priced by the specific region pair.
What triggers this charge
- Cross-region database replication, including Cloud SQL read replicas and Spanner multi-region configurations.
- Reading a Cloud Storage bucket from a service running in a different region — very common when a bucket was created in the default region and the workload was not.
- A multi-region load balancer routing traffic to a backend in another region.
- Cross-region BigQuery reads and dataset copies.
- Disaster-recovery replication, which runs continuously whether or not you ever fail over.
How to reduce it
Co-locate data and compute
The overwhelming majority of avoidable inter-region egress comes from a service in one region reading a bucket or database in another. Moving one of them removes the charge outright rather than reducing it.
Check that multi-region is a decision, not an accident
Multi-region buckets and datasets replicate by default. If the requirement is durability rather than latency, a single region with cross-region backups is usually far cheaper.
Cache across the boundary
Where cross-region reads are genuinely required, a regional cache in front of the remote source turns a per-read charge into a per-refresh charge.
Rates
Related charges
Now find out how much of this you are actually paying.
Finitizer breaks your Google Cloud bill down to the SKU, shows how each one has moved since last week, and separates rate changes from usage changes — so you know whether to talk to engineering or to procurement.