AzureAzure BackupStorage

`azurerm_backup_protected_vm` cost estimation

A VM enrolled in Azure Backup, billed a per-instance protection fee by VM size plus backup storage. A ≤500 GB VM with 100 GB of backups is ~$12/month.

An azurerm_backup_protected_vm enrolls a virtual machine in Azure Backup for scheduled, point-in-time recovery. Cost has two parts: a protected-instance fee tiered by the VM's data size (~$5/month for ≤50 GB, ~$10/month for ≤500 GB, and +$10 per additional 500 GB), plus backup storage (~$0.0224/GB-month LRS) for the recovery points. A ≤500 GB VM with 100 GB of backup storage is ~$10 + $2.24 ≈ $12.24/month.

The protected-instance fee is a fixed per-VM charge; backup storage scales with how much you retain. As with any backup, retention is the storage lever — Azure Backup recovery points are incremental, but long retention on changing VMs accumulates storage, and the instance fee applies per protected VM regardless.

The levers: protect the VMs that need point-in-time restore (not stateless tiers you rebuild from IaC), set retention to compliance need, use LRS storage unless geo-redundancy is required (GRS roughly doubles backup storage), and tier old recovery points to archive where supported.

c3x prices the protected VM from the instance fee (by size) plus backup storage, so the per-VM backup cost is visible.

Terraform example

A minimal but realistic configuration that C3X can estimate.

resource "azurerm_backup_protected_vm" "app" {
  resource_group_name = azurerm_resource_group.recovery.name
  recovery_vault_name = azurerm_recovery_services_vault.main.name
  source_vm_id        = azurerm_linux_virtual_machine.app.id
  backup_policy_id    = azurerm_backup_policy_vm.daily.id
}

Pricing dimensions

What you actually pay for when you provision azurerm_backup_protected_vm.

Dimension	Unit	What's being charged
Protected instance fee	per month	Per-VM fee tiered by data size (~$5 ≤50 GB, ~$10 ≤500 GB, +$10 per extra 500 GB). $10/month for a ≤500 GB VM
Backup storage	per GB-month	Recovery-point storage (~$0.0224/GB-month LRS). Incremental, but grows with retention. ~$0.0224/GB-month → 100 GB ≈ $2.24/month

Sample C3X output

A ≤500 GB VM with 100 GB of backup storage:

azurerm_backup_protected_vm.app
├─ Protected instance fee   1 month       $10.00
└─ Backup storage           100 GB-month   $2.24
                            Monthly       $12.24

Optimization tips

Common ways to reduce azurerm_backup_protected_vm cost without changing the workload.

Protect only VMs that need restore

Per VM not protected

Each protected VM carries the instance fee plus storage. Stateless tiers you can rebuild from IaC often don't need VM backup — reserve it for VMs with data you can't easily reconstruct.

Set retention to compliance need

Per GB-month of retained backups

Backup storage grows with retention. Long daily/weekly/monthly/yearly retention on changing VMs accumulates; set each tier's retention to what recovery and compliance actually require, not the maximum.

Use LRS storage unless you need geo-redundancy

~50% on backup storage vs GRS

GRS backup storage roughly doubles the per-GB rate. Use LRS for VMs where regional backup durability is sufficient; reserve GRS for backups that must survive a regional outage.

Tier old recovery points to archive

Per GB-month of cold backups

Long-retention recovery points can move to the archive tier (much cheaper) where supported, for compliance copies you rarely restore.

FAQ

How is Azure Backup for VMs billed?

A protected-instance fee tiered by the VM's data size (~$5 ≤50 GB, ~$10 ≤500 GB, +$10 per extra 500 GB) plus backup storage (~$0.0224/GB-month LRS). A ≤500 GB VM with 100 GB of backups is ~$12/month.

What drives Azure Backup cost?

The per-VM instance fee (fixed by size) plus retained backup storage. Recovery points are incremental, but long retention accumulates storage, and the instance fee applies per protected VM. Retention and which VMs you protect are the levers.