azurerm_relay_namespace cost estimation

An azurerm_relay_namespace hosts Azure Relay, which securely exposes on-premises services to the cloud without opening inbound firewall ports — via Hybrid Connections (modern, WebSocket-based) or the legacy WCF Relay. Cost is per listener: ~$9.78/month for each connected Hybrid Connection listener, plus a small per-message/overage charge for high volume.

It's an inexpensive service whose cost tracks the number of connected listeners. The standing charge applies per listener that's connected during the month; idle listeners that aren't connected don't accrue the full charge. For most hybrid-connectivity scenarios — exposing an on-prem API or service to an Azure app — a handful of listeners keeps the cost in the tens of dollars.

The lever is simply the listener count: provision Hybrid Connections for the services you actually expose, and don't leave unused connections configured. High-throughput scenarios should watch the message overage, but for typical control-plane connectivity it's negligible.

c3x prices the namespace from the hybrid connection (listener) count, so the cost is visible before deployment.

Terraform example

A minimal but realistic configuration that C3X can estimate.

resource "azurerm_relay_namespace" "main" {
  name                = "hybrid-relay"
  resource_group_name = azurerm_resource_group.main.name
  location            = azurerm_resource_group.main.location
  sku_name            = "Standard"
}

resource "azurerm_relay_hybrid_connection" "onprem_api" {
  name                 = "onprem-api"
  relay_namespace_name = azurerm_relay_namespace.main.name
  resource_group_name  = azurerm_resource_group.main.name
}

Pricing dimensions

What you actually pay for when you provision azurerm_relay_namespace.

Dimension	Unit	What's being charged
Hybrid connection listeners	per listener-month	Per connected listener per month. Idle (disconnected) listeners don't accrue the full charge. $9.78/listener-month → 1 listener = $9.78
Messages	per overage	A per-message overage applies above the included allowance for high-volume relays. Usually negligible for control-plane connectivity.

Sample C3X output

One connected Hybrid Connection listener:

azurerm_relay_namespace.main
└─ Hybrid connection listeners (1)   1 listener-month   $9.78
                                     Monthly            $9.78

Optimization tips

Common ways to reduce azurerm_relay_namespace cost without changing the workload.

Provision listeners only for services you expose

~$9.78/month per unused listener

Cost tracks the listener count (~$9.78 each). Create Hybrid Connections for the on-prem services you actually relay, and remove unused connections — don't leave listeners configured for retired integrations.

Consolidate connectivity where possible

Per avoided listener

If multiple consumers reach the same on-prem service, one Hybrid Connection can serve them rather than provisioning a listener per consumer.

Watch message overage only at high throughput

Pattern-dependent at high volume

For typical control-plane connectivity the per-message overage is negligible. If you relay high-volume data (rather than control signals), check whether the volume warrants a different integration pattern.

FAQ

How is Azure Relay billed?

Per connected listener — ~$9.78/month for each Hybrid Connection listener — plus a small per-message overage above the included allowance for high-volume relays. It's an inexpensive service; cost tracks the number of listeners you connect.

What is Azure Relay used for?

Securely exposing on-premises services to cloud applications without opening inbound firewall ports, via Hybrid Connections (WebSocket-based) or legacy WCF Relay. It's hybrid control-plane connectivity, billed by listener count.

How does c3x estimate the cost?

From the hybrid connection (listener) count, pricing per listener-month. Message overage is usage-driven and usually negligible for typical connectivity.

Related resources

Azure

azurerm_virtual_network_gateway

VPN gateway — full network-level hybrid connectivity vs Relay's service-level

`azurerm_relay_namespace` cost estimation