Azure VNet peering cost: the per-GB charge that bills both ways

Quick answer

Azure VNet peering has no hourly or per-peering fee — you pay per GB of data crossing it, ~$0.01/GB each direction (so ~$0.02/GB round trip) for same-region peering, more for global (cross-region). It bills on both sides. The cost shows up with chatty cross-VNet traffic and hub-and-spoke topologies; co-locating coupled services in one VNet avoids it.

VNet peering looks free at first glance — there's no setup fee and no hourly charge — which is exactly why its cost sneaks up on people. The meter is data, billed in both directions, and a busy hub-and-spoke network can move a lot of GB across peerings without anyone watching the line item.

The meter: data, both ways

Peering charges only for traffic that crosses it: ~$0.01/GB outbound from the sending VNet and ~$0.01/GB inbound at the receiving VNet, for same-region peering. So a GB sent across a peering effectively costs ~$0.02 round trip, split across the two sides. Global VNet peering (different regions) is billed at higher per-GB rates.

Where the cost shows up

Chatty cross-VNet services. Microservices split across VNets that call each other constantly pay peering on every hop.
Hub-and-spoke funnels. Architectures where spoke traffic routes through a hub VNet cross peerings twice — into the hub and out again.
Cross-region over global peering. Replication or services spanning regions pay the higher global rate, continuously.

How to reduce it

Co-locate coupled services in the same VNet. Traffic within a VNet isn't charged; splitting tightly-coupled components across VNets converts free traffic into ~$0.02/GB traffic.
Keep chatty flows in-region. Reserve global peering for traffic that genuinely must cross regions.
Design hub-and-spoke deliberately so high-volume flows don't all transit the hub if a direct path exists.

This is Azure's version of the egress trap covered in GCP egress and AWS data transfer — the cost of moving data sideways, not just out.

FAQ

How much does Azure VNet peering cost?

Peering charges for data in both directions: roughly $0.01/GB inbound and $0.01/GB outbound for traffic between peered VNets in the same region — so effectively ~$0.02/GB round trip. Global (cross-region) VNet peering costs more per GB. There's no hourly or per-peering fee; you pay only for data that crosses the peering.

Is VNet peering charged on both sides?

Yes. Both the sending and receiving VNet incur a charge — the sender pays egress and the receiver pays ingress, each around $0.01/GB for same-region peering. A common surprise is forgetting that a chatty service calling across a peering pays at both ends.

Why is my VNet peering bill higher than expected?

Usually a hub-and-spoke topology where lots of traffic crosses peerings, or chatty microservices split across VNets. Every GB between peered VNets bills both ways, so high inter-VNet traffic adds up. Co-locating tightly-coupled services in one VNet avoids the charge entirely.

Does global VNet peering cost more?

Yes. Peering VNets in different regions (global peering) is billed at higher per-GB rates than same-region peering, reflecting cross-region transport. Cross-region replication or chatty services spanning regions over global peering can become a significant line item.

How do I reduce VNet peering costs?

Co-locate tightly-coupled services in the same VNet, keep chatty traffic within a region rather than over global peering, use private endpoints or service endpoints where they avoid peered hops, and design hub-and-spoke so high-volume flows don't all funnel through peerings. Minimizing inter-VNet data is the lever.

How does C3X account for peering cost?

Peering cost is data-driven, so C3X models it from expected inter-VNet GB in c3x-usage.yml and prices the VNets and connected resources, helping you attribute cross-VNet transfer to the architecture that generates it.

What to do next

Peering cost tracks inter-VNet data, so attribute it to the architecture and model the volume. C3X prices your azurerm_virtual_network and connected resources and takes peering volume from c3x-usage.yml, so a chatty cross-VNet design shows its data cost before it ships. The quickstart runs it in minutes.