VPC Peering Calculator

full mesh connections = n(n − 1) ÷ 2; each VPC terminates n − 1 peerings and needs n − 1 route entries. VPC peering is not transitive: traffic cannot hop through a peered VPC to reach a third one, so any-to-any connectivity requires a full mesh of n(n − 1) ÷ 2 connections. The route table burden grows with it, because every VPC needs an explicit route to every peer, and peering has no hourly charge — you pay only for data transfer, which is free within an Availability Zone and charged per GB across regions.

The quadratic growth is the whole argument for a Transit Gateway: eight VPCs need 28 peerings and 56 route entries, while twenty need 190 peerings that no team can audit by hand.

This calculator takes 4 inputs: VPCs to interconnect, Active peerings per VPC quota, Cross-region data transfer per month, Price per GB transferred cross-region. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.

Once the mesh passes roughly five to ten VPCs, or as soon as you need transitive routing, shared VPN and Direct Connect, or centralised inspection. Peering stays attractive for a small number of high-bandwidth pairs because it has no hourly or data processing charge.

No. A peering connection has no hourly charge. You pay only for data transfer, and traffic between Availability Zones or regions is charged at the standard rates — confirm the current per-GB figures for your regions with AWS.