AzureAzure ExpressRouteNetworking

`azurerm_express_route_circuit` cost estimation

A private, dedicated connection between on-premises and Azure. Priced as a monthly circuit fee by bandwidth and billing model, plus outbound data on the metered plan.

An azurerm_express_route_circuit is a private connection into Azure that bypasses the public internet, used for hybrid networking, predictable latency, and high-throughput data movement. The cost has two shapes depending on the billing model you choose.

On the Metered plan, you pay a fixed monthly circuit fee by port bandwidth (for example, ~$436/month for 1 Gbps, ~$290 for 500 Mbps, ~$5,700 for 10 Gbps) plus per-GB outbound data transfer. Inbound is free. On the Unlimited plan, you pay a higher fixed monthly fee and outbound data is included, which wins above a break-even throughput. The bandwidth tier is the dominant cost in both models.

c3x prices the fixed circuit fee from the bandwidth_in_mbps setting (Zone 1 rates). Outbound data on the metered plan is usage-based and supplied in c3x-usage.yml. Note that ExpressRoute also requires a gateway on the Azure side (a virtual network gateway), which bills separately, and the connectivity provider charges their own port fee outside Azure.

Terraform example

A minimal but realistic configuration that C3X can estimate.

resource "azurerm_express_route_circuit" "onprem" {
  name                  = "onprem-er"
  resource_group_name   = azurerm_resource_group.net.name
  location              = "eastus"
  service_provider_name = "Equinix"
  peering_location      = "Washington DC"
  bandwidth_in_mbps     = 1000

  sku {
    tier   = "Standard"
    family = "MeteredData"
  }
}

Pricing dimensions

What you actually pay for when you provision azurerm_express_route_circuit.

Dimension	Unit	What's being charged
Circuit fee (metered)	per month	Fixed monthly fee by port bandwidth on the metered plan. c3x prices from bandwidth_in_mbps at Zone 1 rates. $436/mo (1 Gbps), $5,700/mo (10 Gbps)
Outbound data transfer	per GB	Egress on the metered plan; inbound is free. Usage-based. Unlimited-plan circuits include outbound in the higher fixed fee.
Gateway (separate resource)	per hour	ExpressRoute requires a virtual network gateway on the Azure side, billed separately as azurerm_virtual_network_gateway.

Sample C3X output

Example output from c3x estimate (1 Gbps metered):

azurerm_express_route_circuit.onprem
└─ Circuit fee (1 Gbps, metered)    1  month    $436.00

OVERALL TOTAL                                   $436.00
(outbound data & gateway billed separately)

Optimization tips

Common ways to reduce azurerm_express_route_circuit cost without changing the workload.

Pick Metered vs Unlimited by throughput

Plan break-even

Metered is cheaper below the break-even egress volume; Unlimited wins for sustained high outbound. Estimate your monthly egress and compare the fixed-plus-data metered cost against the flat Unlimited fee.

Right-size the bandwidth tier

Tier delta (large)

The port bandwidth is the dominant fixed cost and jumps sharply between tiers. Provision the tier that matches sustained throughput, not peak bursts you can absorb with buffering.

Share one circuit across workloads

Per avoided circuit

A single circuit with multiple peerings serves many VNets via an ExpressRoute gateway. Don't provision separate circuits per workload when one tier covers aggregate throughput.

FAQ

How does c3x estimate ExpressRoute cost?

It prices the fixed monthly circuit fee from bandwidth_in_mbps (metered plan, Zone 1 rates). Outbound data on the metered plan is usage-based, and the required virtual network gateway is priced as its own resource.

What's the difference between Metered and Unlimited?

Metered has a lower fixed fee plus per-GB outbound charges. Unlimited has a higher fixed fee with outbound included. Above a throughput break-even, Unlimited is cheaper; below it, Metered wins.

Is the ExpressRoute gateway included in the price?

No. ExpressRoute needs a gateway on the Azure VNet side, which bills separately as azurerm_virtual_network_gateway (an ExpressRoute gateway SKU). c3x prices it as its own resource.

Does Azure charge for inbound data?

No. On the metered plan, inbound (ingress) data is free; only outbound (egress) is billed per GB. Unlimited includes outbound in the fixed fee.

Does the connectivity provider cost extra?

Yes, outside Azure. Your ExpressRoute partner (Equinix, Megaport, a telco) charges their own port and cross-connect fees, which aren't part of the Azure bill c3x estimates.