AWS to Azure Migration: Real Timeline, Costs, and Risks in 2026

AWS to Azure Migration: What It Actually Costs and Takes

AWS to Azure migrations are more common than most IT professionals expect. The drivers vary: Microsoft 365 consolidation (wanting identity and productivity in the same cloud), EA/MCA agreement incentives, ERPNext or Dynamics deployments that benefit from Azure proximity, or simply a strategic decision to reduce multi-cloud complexity.

This post covers what the migration actually involves — timeline, cost, and what goes wrong — based on migrations Techseria has completed in 2024–2026.

What Migrates Cleanly

Virtual machines: AWS EC2 to Azure VMs migrates well using Azure Migrate. The service discovers EC2 instances, assesses them for Azure VM SKU compatibility, and replicates them. Expect 4–8 hours per VM for initial replication, then delta sync until cutover. Databases: RDS to Azure SQL or Azure Database for MySQL/PostgreSQL migrates using Azure Database Migration Service. Simple schemas with no exotic features migrate in hours. Complex schemas with stored procedures, triggers, and linked servers require more assessment. Object storage: S3 to Azure Blob Storage is straightforward using AzCopy. Transfer speed depends on data volume and network bandwidth. Static files, backups, and logs migrate cleanly.

What Requires Significant Rework

AWS-specific services: Lambda functions → Azure Functions (requires rewriting handlers and deployment packages). SQS/SNS → Azure Service Bus or Event Grid (different SDK and message format). DynamoDB → Azure Cosmos DB (schema and query pattern changes required). ElasticSearch (OpenSearch) → Azure AI Search (significant API differences). CloudFormation/CDK → Azure Resource Manager or Bicep (full IaC rewrite). IAM policies → Azure RBAC and Azure AD (different permission model, must be fully redesigned). DNS and CDN: Route 53 → Azure DNS and Azure Front Door. Domain transfers can take 5–7 days. CDN configurations must be recreated. Certificate management moves to Azure Key Vault or App Service certificates.

Timeline: What to Expect

Small environment (10–20 VMs, 3–5 applications, minimal AWS-native services): 6–10 weeks. Medium environment (20–50 VMs, 10–20 applications, moderate AWS-native service usage): 12–20 weeks. Large environment (50+ VMs, complex microservices, heavy AWS-native services): 6–18 months.

The most common schedule slip is underestimating application-level rework. Infrastructure migrates faster than expected; application dependencies and AWS SDK calls in application code take longer than expected.

Cost Breakdown

Migration project cost (Techseria): Small environment: £15,000–£35,000. Medium environment: £35,000–£90,000. Large environment: £90,000–£300,000+.

AWS ongoing costs during migration (running both environments during transition): typically 1.3–1.8x your current AWS bill for the migration period. Azure commitment: most migrations achieve Azure costs 10–25% lower than the equivalent AWS spend, due to Azure Hybrid Benefit (Windows/SQL licensing), reserved instance pricing, and Azure Dev/Test pricing for non-production workloads.

The Three Most Common Migration Failures

1. No cutover rehearsal. The migration team practises the technical steps but never rehearses the actual cutover sequence — DNS switch, application reconfiguration, smoke testing — under time pressure. On cutover day, the sequence takes 3x longer than planned. Mitigation: rehearse the cutover in a staging environment with a time limit.

2. IAM policy translation errors. AWS IAM policies don't map 1:1 to Azure RBAC. Too-broad translations create security gaps; too-strict translations break applications. Mitigation: audit every IAM policy and translate manually with application-level testing.

3. Underestimating data transfer costs. Large data volumes in AWS incur significant egress costs when transferring to Azure. A 50TB transfer at AWS egress rates (£0.07–£0.08/GB) costs £3,500–£4,000 in egress alone. Mitigation: use AWS Direct Connect or physical data transfer (AWS Snowball) for large volumes.

Planning an AWS to Azure migration? Book a Strategy Session with Techseria — we'll assess your environment and give you a realistic timeline and cost estimate within 5 working days.