AzureAzure Managed DisksStorage

`azurerm_managed_disk` cost estimation

A block storage disk for Azure VMs. Priced by disk type and tier (per-disk for Premium SSD, per-GB for Standard).

An azurerm_managed_disk is a network-attached block storage disk for Azure VMs. Pricing has a unique tier-based structure that differs from AWS EBS or GCP Persistent Disk.

Disk types and pricing models:

Standard HDD (storage_account_type = "Standard_LRS"): $0.05/GB-month. Right for backup, dev, infrequent access. Magnetic disks, lowest performance.

Standard SSD ("StandardSSD_LRS"): $0.075/GB-month. Right for non-production workloads needing SSD performance. Cheaper than Premium but with lower IOPS.

Premium SSD ("Premium_LRS"): tier-based pricing, not per-GB. Each tier (P1 through P80) has a fixed monthly cost and fixed IOPS/throughput. P10 (128 GB) is $19.71/month; P30 (1 TB) is $135/month. Choosing a tier larger than your data needs is wasted cost.

Premium SSD v2 ("PremiumV2_LRS"): per-GB plus per-provisioned-IOPS plus per-provisioned-MB/s. More flexible than Premium SSD. Right for workloads that need higher IOPS than the size tier provides.

Ultra Disk ("UltraSSD_LRS"): per-GB-month + per-IOPS-month + per-MB/s-month. Highest performance tier. Right for SAP HANA and other high-IOPS databases.

Zone-redundant variants (ZRS suffix) cost roughly 50% more for cross-zone redundancy.

Snapshots and disk reservations are separately billable resources.

c3x reads storage_account_type and disk_size_gb. For Premium SSD, it maps size to the appropriate tier (P-tier). For Premium SSD v2 and Ultra, IOPS and throughput attributes come from the disk_iops_read_write and disk_mbps_read_write attributes.

Terraform example

A minimal but realistic configuration that C3X can estimate.

resource "azurerm_managed_disk" "data" {
  name                 = "data-disk"
  resource_group_name  = azurerm_resource_group.main.name
  location             = "eastus"
  storage_account_type = "Premium_LRS"
  create_option        = "Empty"
  disk_size_gb         = 256

  tags = {
    Environment = "production"
  }
}

resource "azurerm_virtual_machine_data_disk_attachment" "data" {
  managed_disk_id    = azurerm_managed_disk.data.id
  virtual_machine_id = azurerm_linux_virtual_machine.api.id
  lun                = "10"
  caching            = "ReadWrite"
}

Pricing dimensions

What you actually pay for when you provision azurerm_managed_disk.

Dimension	Unit	What's being charged
Standard HDD	per GB-month	Magnetic storage. Cheapest tier. Right for backup or cold data. $0.05/GB-month for LRS
Standard SSD	per GB-month	SSD performance at lower cost than Premium. Per-GB pricing. $0.075/GB-month
Premium SSD	per disk tier per month	Tier-based: P1 through P80. Each tier has fixed IOPS, throughput, and price. Not per-GB. $19.71/month for P10 (128 GB), $135/month for P30 (1 TB)
Premium SSD v2	per GB + per IOPS + per MB/s	Decoupled performance billing. Right when IOPS/throughput needs don't match tier sizes.
Ultra Disk	per GB + per IOPS + per MB/s	Highest performance tier. Right for SAP HANA, high-IOPS databases.

Optimization tips

Common ways to reduce azurerm_managed_disk cost without changing the workload.

Choose Premium SSD tier carefully

Up to 50% per tier reduction

Premium SSD pricing is tier-based, not per-GB. A 130 GB disk gets billed as P15 (256 GB) because it crossed the 128 GB threshold. Right-sizing to 128 GB or below saves a tier.

Use Standard SSD for non-production

About 67% on non-prod

Standard SSD has 99% of the production performance of Premium SSD for typical web app workloads at one-third the cost. Right for dev/staging.

Migrate Premium SSD to Premium SSD v2 for high-IOPS workloads

Workload-dependent

Premium SSD v2 lets you provision IOPS independently of capacity. For a 500 GB disk needing 10,000 IOPS, v2 is often cheaper than the P-tier required for those IOPS.

Delete unattached disks

100% of cost on stale disks

Detached managed disks continue to bill. Audit periodically for orphaned disks from deleted VMs.

Use ZRS only for HA-critical disks

33% by choosing LRS

Zone-redundant storage costs 50% more. For application-replicated data (Cassandra, Postgres replicas), LRS is sufficient. ZRS is right for stateful systems without app-level redundancy.

FAQ

Why is Premium SSD pricing tier-based?

Azure prices Premium SSDs by performance tier, not by raw GB. Each tier (P1 through P80) bundles a specific size with specific IOPS and throughput. Stepping over a tier boundary jumps you to the next tier's full price even if you only needed slightly more capacity.

How does c3x handle Premium SSD tier mapping?

c3x reads disk_size_gb and maps it to the smallest P-tier that fits. For example, 130 GB maps to P15 (256 GB tier). The tier price is what c3x reports.

Premium SSD v2 vs Premium SSD?

v2 is newer and uses per-GB + per-IOPS + per-MB/s pricing. v1 is tier-based. v2 is often cheaper for workloads that need specific IOPS levels rather than just capacity. v1 is simpler but less flexible. New deployments should consider v2.