Azure to AWS is the less common cross-cloud direction. The structural reason is licence economics: most Azure estates concentrate on Microsoft-licensed workloads, and the loss of Azure Hybrid Benefit on the AWS side adds 15 to 25 percent to the steady-state Windows and SQL Server cost. For non-Microsoft estates the comparison is more balanced, and the migration cost reduces to the standard cross-cloud line items: egress, identity, networking, and managed service conversion. This page covers both cases.
Cost is rarely the leading driver. In the migrations this site catalogues across publicly available customer references and partner case studies, four drivers dominate. First, post-acquisition consolidation, where the acquiring organisation runs on AWS and the acquired organisation runs on Azure. Second, deliberate AWS-native service preference, typically for Amazon Aurora, EKS Anywhere, AWS Lake Formation, or specific Bedrock model access. Third, commercial leverage in a multi-cloud RFP process, where the threat of migration drives down committed-use pricing. Fourth, regulatory or sovereign cloud requirements that AWS GovCloud or AWS Sovereign Cloud (announced) addresses more directly than Azure equivalents in specific regions.
The financial case for the migration rarely closes on steady-state cost alone. AWS and Azure compute on like-for-like SKUs land within 5 percent of each other for non-Microsoft workloads. For Microsoft workloads Azure typically wins by 15 percent or more once Hybrid Benefit is applied. The one-time cost of the cross-cloud move frequently exceeds 18 months of steady-state saving on non-Microsoft workloads and is structurally unrecoverable on Microsoft-heavy workloads.
Azure outbound data transfer pricing is structured by region zone and volume tier. Zone 1 (Americas, Europe, UK, France, South Africa) is the headline tier. The first 100 GB per month per subscription is free; the first 10 TB beyond that is $0.087 per GB; the next 40 TB is $0.083; the next 100 TB is $0.07; and everything above 350 TB is $0.05 per GB. The structure is documented in the public Azure bandwidth pricing page. The rates are broadly comparable with AWS DTO but with a more generous free tier and a slightly cheaper top-band rate.
Azure to AWS egress cost by dataset size, single-month transfer
| Dataset | Azure outbound rate (blended) | Cost | Notes |
|---|---|---|---|
| 5 TB | $0.087 per GB | $444 | First 100 GB free, rest at first-tier rate |
| 20 TB | $0.085 blended | $1,732 | 10 TB at $0.087, 10 TB at $0.083 |
| 50 TB | $0.077 blended | $3,929 | Blended across first three tiers |
| 100 TB | $0.071 blended | $7,229 | Most in the $0.07 tier |
| 200 TB | $0.063 blended | $12,800 | Some in $0.05 tier |
| 500 TB | $0.057 blended | $28,997 | Larger portion in $0.05 tier |
| 1 PB | $0.054 blended | $55,116 | Most in $0.05 tier |
Azure Data Box for export
The single most material cost difference between Azure and AWS for Microsoft workloads is how Windows Server and SQL Server licences are handled. Azure Hybrid Benefit lets customers with Software Assurance reuse existing licences on Azure compute at a reduced rate. AWS has no direct equivalent. BYOL on AWS requires EC2 Dedicated Hosts, which carry a tenancy premium (a dedicated host typically costs 15 to 40 percent more per equivalent vCPU-hour than shared tenancy) and impose minimum capacity commitments that erode the licence saving on small estates.
For a 100-VM Windows Standard estate, the licence cost on AWS shared-tenancy License Included is roughly $185K per year for typical D-equivalent SKU sizes. The Azure equivalent with Hybrid Benefit applied is approximately $0 (the licences are already owned). The $185K per year delta is permanent unless the estate moves to a different OS, which is rarely realistic for Windows-specific applications. For SQL Server the per-VM premium is higher still, with typical estates seeing $300 to $1,200 per VM per month of incremental cost on AWS versus Azure Hybrid Benefit.
Most Azure estates use Microsoft Entra ID as the identity provider, with Azure RBAC for resource authorisation. AWS uses AWS Identity and Access Management (IAM) for resource authorisation, with AWS IAM Identity Center as the federation broker for external identity providers. The two models do not translate one-for-one and require deliberate design work to bridge.
The three common patterns. First, maintain Entra ID as the identity master, federate to AWS via AWS IAM Identity Center using SAML 2.0. This is the lowest-friction pattern and the one AWS recommends. Second, migrate identities into AWS Managed Microsoft AD, replicate from Entra ID via Entra Connect, and decommission the Entra ID dependency over time. This is structurally heavier but produces full independence from Azure. Third, deploy a third-party IdP like Okta or PingFederate as the bridge, federate both Entra ID and AWS IAM IC to it. This adds licence cost but is common in larger estates that already have a multi-cloud IdP strategy.
The cost shape varies materially by pattern. Federation via SAML costs $30K to $80K of identity engineering effort. Managed AD migration costs $120K to $400K depending on the number of forests, trusts, and Group Policy Object dependencies. Third-party IdP deployment adds licence cost of roughly $4 to $12 per user per month plus deployment effort.
For Microsoft-heavy estates the database conversion is the largest single line item after identity. Azure SQL Managed Instance and AWS RDS for SQL Server use the same underlying SQL Server engine, so the data migration via AWS Database Migration Service is straightforward. The cost concentrates in the licence flip (SQL MI uses Azure Hybrid Benefit, RDS for SQL Server uses License Included by default and BYOL on Dedicated Hosts requires a tenancy decision), application-side connection string updates, and feature parity validation (Azure SQL MI has some PaaS features that RDS for SQL Server does not, like always-on managed backups to long-term retention).
A typical 5 TB SQL Managed Instance database moves to AWS RDS for SQL Server in three to six weeks of parallel running. The Azure egress cost on the data is roughly $440. The DMS replication cost is roughly $1,300 over the replication window. Partner-led conversion and validation typically lands at $8,000 to $25,000 per database depending on schema complexity and application coupling. The ongoing licence cost increase on the AWS side is the largest single line item: typically $150 to $400 per vCPU per month of incremental cost compared with Azure SQL MI with Hybrid Benefit.
A representative cost build for a 50-server Azure to AWS migration, post-acquisition consolidation scenario, 50 TB of data across Blob and Azure SQL MI, mixed strategy (70 percent rehost on EC2, 20 percent replatform to managed AWS services, 10 percent retire), 9-month programme. Hybrid Benefit assumed in place pre-migration, lost post-migration on Windows and SQL Server workloads.
Worked Azure to AWS cost build, 50 servers, 50 TB, 9 months
| Cost line | Low estimate | Typical estimate | High estimate |
|---|---|---|---|
| Assessment and planning (Migration Evaluator + partner) | $35,000 | $60,000 | $120,000 |
| Azure egress (50 TB at blended $0.077 per GB) | $3,500 | $3,900 | $4,400 |
| Migration labour, 45 workloads, blended | $320,000 | $640,000 | $1,150,000 |
| IAM federation and AD migration | $60,000 | $180,000 | $400,000 |
| Azure SQL MI to RDS conversion (5 databases) | $25,000 | $80,000 | $180,000 |
| Functions to Lambda refactor (8 functions) | $15,000 | $45,000 | $95,000 |
| Parallel running (4 months, Azure + AWS both live) | $120,000 | $240,000 | $460,000 |
| Cutover and downtime contingency | $30,000 | $65,000 | $160,000 |
| AWS Enterprise Support (9 months) | $85,000 | $130,000 | $170,000 |
| Staff retraining (5 engineers) | $15,000 | $28,000 | $48,000 |
| Security rework (Security Hub, GuardDuty, IAM) | $30,000 | $80,000 | $170,000 |
| Contingency at 15 percent | $115,000 | $240,000 | $470,000 |
| AWS MAP partner funding | ($100,000) | ($180,000) | ($350,000) |
| Net total estimate | $753,500 | $1,611,900 | $3,077,400 |
The typical-column number is similar to the AWS to Azure scenario in magnitude. The structural difference is downstream: this migration adds roughly $200K to $500K per year of incremental Windows and SQL Server licensing cost on the AWS side that did not exist on the Azure side. The cumulative 3-year licence cost penalty often exceeds the migration cost itself.
Azure to AWS is structurally the more expensive direction for Microsoft-heavy estates and the most cost-neutral direction for AWS-native or open-source-heavy estates. Cost is rarely the leading driver; consolidation, commercial leverage, or specific service preference are typically what move the decision. The discipline that makes the migration cost work is the same as for every cross-cloud move: retire aggressively, stage egress sensibly, and compress the cutover window.
A. A 50-server, 50 TB Azure to AWS migration typically costs $250K to $850K over a 6 to 12 month programme. The cost shape is similar to AWS to Azure but with two structural differences: Azure egress is slightly cheaper than AWS egress at the headline rate, and the loss of Azure Hybrid Benefit on the destination side often makes the steady-state AWS cost 15 to 25 percent higher than the source Azure cost.
A. On AWS, BYOL Windows or SQL Server requires EC2 Dedicated Hosts, which carry a tenancy premium. For a 100-VM Windows estate, moving from Azure (with Hybrid Benefit) to AWS adds roughly $200K per year of incremental Windows licensing cost compared with Azure pay-as-you-go without Hybrid Benefit. The full Hybrid Benefit saving disappears on the destination side; the licence economics are why few Microsoft-heavy estates move from Azure to AWS in practice.
A. Azure publishes the outbound data transfer rate at $0.087 per GB for the first 10 TB per month in zone 1 (Americas, Europe, UK), dropping to $0.083 for the next 40 TB, $0.07 for the next 100 TB, and $0.05 above 350 TB. The first 100 GB per month per region is free. For a 50 TB cross-cloud move the egress cost is roughly $4,200, broadly comparable with AWS egress in the reverse direction.
A. AWS offers AWS Managed Microsoft AD as the destination for Entra ID federation or Active Directory replication. The federation pattern is the most common: maintain Entra ID as the identity master, federate to AWS via SAML 2.0 or AWS IAM Identity Center. Workload migration then requires re-registering applications with the AWS-side identity provider. For applications using on-premise Active Directory via Entra Connect, the AWS Managed Microsoft AD service mirrors the directory structure at roughly $0.40 per hour per directory plus per-domain-controller costs.
A. The four most common drivers are (1) consolidating on a single AWS-based cloud strategy after an acquisition, (2) accessing AWS-native services like Amazon Aurora, EKS, or specific analytics offerings that the customer prefers over Azure equivalents, (3) commercial leverage in a multi-cloud RFP, and (4) regulatory or sovereignty requirements that AWS addresses more directly in specific regions. Cost alone rarely justifies the move; AWS typically becomes more expensive after the Hybrid Benefit loss on Microsoft workloads.
A. Yes. AWS Application Migration Service (MGN) supports Azure virtual machines as a source. The MGN agent replicates the source VM into AWS continuously, providing a near-zero RPO and a sub-hour cutover window. MGN is free for the first 90 days per server; thereafter the replication cost is roughly $0.028 per source server per hour, plus the cost of the EBS staging area and the cutover target EC2 instance.
AWS vs Azure vs GCP ->
Side-by-side identical scenario
AWS to Azure (reverse) ->
Egress, IAM, RDS conversion
On-prem to AWS ->
MAP credits, EC2, Snowball
AWS migration cost ->
EC2, MAP credits, DataSync
Azure migration cost ->
Hybrid Benefit, FastTrack
AWS MGN cost ->
Free-for-90-days window
AWS Snowball cost ->
Per-device, egress break-even
10 hidden costs ->
Detailed playbook
Strategy cost tables ->
7Rs framework
Updated 2 May 2026