Stop Treating Cloud Migration as a Cost-Saving Project

I keep hearing the same thing from IT leaders: “We’re migrating to the cloud to save money.” That belief is wrong, and it’s costing companies millions. The cloud doesn’t automatically reduce costs; in fact, it often increases them unless you actively manage spend. Flexera’s 2025 State of the Cloud report found that 84% of organizations say managing cloud spend is their top challenge, and cloud budgets exceeded limits by 17%. If migration were a magic cost-saver, that number wouldn’t be so high.

My thesis is simple: cost optimization in cloud migration is not a phase you complete; it’s a discipline you practice from day one. And the most effective way to start is to replatform, not rehost. Rehosting—lift and shift—moves applications as-is, which is fast and simple, but it doesn’t leverage cloud-native features and often leads to higher long-term costs. Red Hat notes that rehosting without modification can increase long-term costs because you’re running applications in the cloud without cloud-native capabilities. So if you’re migrating just to save money, rehosting is a trap.

The Rehost Illusion

Rehosting is popular because it’s quick and low-risk. AWS says you can migrate large numbers of machines without long cutover windows. But speed doesn’t equal savings. A rehosted application still runs on the same architecture, just in a different location. You pay for cloud resources that you’re not fully utilizing. Red Hat’s survey found that 38% of organizations plan to rehost, then replatform, then refactor—essentially admitting they’ll need to optimize later. Why not optimize during migration? Because it’s harder. But the payoff is real.

Replatform: The Sweet Spot for Cost Optimization

Replatforming—making minor optimizations like switching to a cloud-managed database—is the most common migration approach, according to Red Hat, at 20%. And for good reason. It’s the Goldilocks strategy: you get meaningful cost benefits without the full rewrite of refactoring. AWS gives concrete examples: moving SQL Server to Amazon RDS, using Graviton processors, or porting .NET Framework to .NET Core on Linux. These changes can cut your compute and licensing costs significantly. I’ve seen teams reduce their database spend by 30% just by moving to a managed service. That’s not magic; that’s replatforming.

The Counterargument: Refactor for Maximum Savings

Some will argue that refactoring—re-architecting for cloud-native—delivers the greatest savings. AWS calls it the most complex and costly strategy. Yes, refactoring can yield the biggest benefits, but it’s also the riskiest and most expensive upfront. For large migrations, AWS explicitly recommends against refactoring because it’s too complex to manage across many applications. Unless you have a single, high-value application that justifies the investment, refactoring is not a cost-optimization strategy; it’s a modernization strategy. I reject it as a default path for cost savings.

You Can’t Optimize What You Don’t Measure

Here’s the hard truth: cost optimization requires ongoing measurement. Flexera 2026 reports that wasted cloud spend on IaaS and PaaS rose to 29%—the first increase after five years of decline. That’s because organizations aren’t tracking effectively. The same report shows 63% have a dedicated FinOps team and 71% have a Cloud Center of Excellence. If you don’t have one, you’re already behind. And don’t just measure total spend; measure unit economics—49% of organizations now link cloud cost to business outcomes. That’s how you know if you’re actually saving money.

Quick tip: Before you migrate, calculate your total cost of ownership (TCO) using a tool like the Azure TCO Calculator. Azure Migrate assessments include cost estimation and right-sizing. You can’t optimize what you haven’t estimated.

Start with Assessment, Not Assumptions

The assessment phase is where cost optimization begins. Microsoft’s Azure migration framework starts with Assess, which includes creating a full inventory and dependency map and estimating cost savings using the TCO Calculator. AWS’s assess phase helps you build a migration plan and foundation. If you skip this, you’ll miss dependencies and overspend. DigitalOcean warns that under-assessing the application portfolio leads to missed dependencies. So do the boring work upfront.

The table makes it clear: replatform offers the best balance of cost savings and effort. Rehost is a starting point, not a destination. Refactor is for when you have budget and time.

One more thing: don’t forget to retire zombie applications. AWS defines zombie applications as those with average CPU and memory usage below 5% and idle applications as 5-20% usage over 90 days. These are pure waste. Retiring them is the easiest cost savings you’ll ever get.

So my recommendation: plan for replatforming as your primary strategy, measure everything with FinOps, and retire the junk. The cloud can save you money, but only if you treat cost optimization as a continuous practice, not a one-time project.

The single most important thing to remember: migration doesn’t cut costs; optimization does. And optimization never stops.

Sources

• Flexera 2025 - https://www.flexera.com/about-us/press-center/new-flexera-report-finds-84-percent-of-organizations-struggle-to-manage-cloud-spend
• Red Hat - https://www.redhat.com/en/blog/how-should-you-modernize-your-applications
• AWS Prescriptive Guidance - https://docs.aws.amazon.com/prescriptive-guidance/latest/large-migration-guide/migration-strategies.html
• Flexera 2026 - https://www.flexera.com/blog/finops/the-new-era-of-cloud-what-2026-data-tells-us-about-spend-scale-and-strategy/
• Microsoft Learn - https://learn.microsoft.com/en-us/training/modules/design-migrations/3-describe-azure-migration-framework
• DigitalOcean - https://www.digitalocean.com/resources/articles/cloud-migration-checklist