Azure Site Recovery Pricing UK 2026

1. The four components of ASR cost — and why only one is on the pricing page

The Azure Site Recovery pricing page shows a single per-instance fee. For Azure VMs it looks affordable — £18.87/month per VM. What the pricing page doesn't show is that the per-instance fee is typically the smallest component of your actual DR bill. Once you add replica managed disk storage in the target region, ongoing delta replication transfer between regions, and the compute cost of quarterly failover tests, the total is commonly 3–4× the per-instance fee. The calculator exists to show all four components together — because building a DR business case on the per-instance fee alone will underestimate the real cost significantly.

The replica storage component is often the largest single line item — for a VM with a 256 GB disk, replica storage alone at Standard HDD LRS costs £8.32/month versus the £18.87 instance fee. Once you include GRS redundancy or multiple disks, replica storage can exceed the instance fee entirely.

2. Per-instance fees — Azure VMs vs on-premises, and the 31-day free trial

The per-instance fee is £18.87/month (derived from $25 USD at the Microsoft implied GBP rate of 0.7548). This applies to Azure VMs, on-premises Hyper-V and VMware VMs, and instances of SQL Server and SAP HANA that you want to protect.

Each newly protected instance has a 31-day free trial. This is designed to cover the initial replication window — ASR needs to send the full disk to the target region before delta replication begins. During the trial, you only pay for storage and transfer, not the instance fee. From day 32, the monthly instance fee begins.

3. Replica storage — why it's often the largest component

ASR maintains a complete replica of each protected disk in the target region. The replica is a Standard HDD managed disk by default — appropriate for DR since it doesn't serve live traffic. The disk is the same size as the source (or larger if the source expands). You pay the managed disk rate continuously, not just during active replication.

LRS is the typical choice for DR replica disks. The DR region itself provides geographic redundancy — adding GRS on top of that is redundancy of redundancy. Use the Managed Disks calculator to model different disk sizes and types precisely.

4. Replication data transfer — initial vs delta

ASR transfer happens in two phases. Initial replication sends the complete disk to the target region — for a 256 GB disk, that is a one-off 256 GB transfer at £0.015/GB = £3.84. This is typically the largest single transfer event and occurs once per protection setup.

Delta replication is the ongoing cost — only changed blocks are sent, typically 5–20 GB/month for a busy VM and under 5 GB/month for a quiescent server. At £0.015/GB (UK South → UK West cross-region rate from D1), 10 GB/month of delta replication costs £0.15/month — a minor line item. The initial replication transfer is more significant and worth modelling separately for the onboarding budget.

Use the Bandwidth calculator for detailed transfer cost modelling including the initial replication event.

5. Failover test compute — why regular testing is non-negotiable and what it costs

DR without testing is not DR — it is hope. Microsoft recommends at least two failover tests per year. For critical workloads with an RTO/RPO SLA, quarterly testing is standard. During a test failover, ASR spins up VMs in the target region and runs them for the duration of the test. These VMs are billed at normal compute rates.

For a 4-hour quarterly test of 5 D2s v3 VMs at £0.073/hr: 4 × 5 × £0.073 = £1.46 per test, £5.84/year, £0.49/month annualised. At this scale, failover compute is the smallest line item. At larger scales — 50 VMs, D8s v3, 8-hour tests — it becomes more material: £233.60/test, £77.87/month.

6. Azure Hybrid Benefit — who qualifies and how much it saves

If you are protecting on-premises Windows Server VMs and you have active Software Assurance on your Windows Server licences, Azure Hybrid Benefit applies. It reduces the Windows licensing component of the VM compute cost — approximately 30% of the instance fee for eligible on-premises workloads. SQL Server licences with active SA also qualify for AHB on the SQL Server compute cost.

Azure VMs that you are protecting within Azure (Azure-to-Azure replication) do not receive AHB on the ASR instance fee — the licensing model is different. AHB applies most clearly to on-premises to Azure DR scenarios.