Calculating the ROI of Switching from On-Prem to IaaS

On-Prem to IaaS Migration: How to Calculate Cost

Calculating the ROI of switching from on-prem to IaaS is a common exercise IT leaders face when taking on an infrastructure modernization project. The real ROI conversation involves a mix of hard costs, avoided costs, and risk reduction that rarely shows up on a standard budget line.

Why the On-Prem Cost Comparison Is Incomplete

Most organizations start their ROI analysis by comparing server, storage, and networking hardware costs to a monthly IaaS invoice. The costs that are harder to see, and often larger, include:

1. Hardware refresh cycles every three to five years, including the capital outlay and the internal project time to plan, procure, and migrate
2. Data center overhead: power, cooling, physical security, and floor space
3. Software licensing tied to specific hardware generations
4. Staff time spent on patching, firmware updates, and capacity planning instead of strategic work
5. Downtime risk when aging hardware fails outside of a maintenance window
6. The opportunity cost of IT staff maintaining infrastructure instead of supporting the business

A complete ROI calculation must account for all of these, not just the sticker price of a server refresh.

Step 1: Establish Your True On-Prem Baseline

Before you can calculate savings, you need an accurate picture of what your current environment costs. Pull together:

1. Capital costs: Depreciation schedules for existing servers, storage arrays, and networking gear, plus any refresh spend planned in the next 12 to 24 months
2. Operating costs: Power, cooling, facility space, and any colocation fees
3. Labor costs: The percentage of your IT team’s time spent on infrastructure maintenance versus application support, security, or strategic projects
4. Risk costs: Estimated cost of downtime per hour, based on past incidents, multiplied by your historical downtime hours per year
5. Compliance costs: Audit prep time, documentation, and any consulting fees tied to maintaining certifications on your own infrastructure

This baseline is usually where organizations discover their real infrastructure spend is significantly higher than what shows up in the IT capex budget alone.

Step 2: Model the IaaS Side of the Equation

On the IaaS side, the calculation is more straightforward because most of the cost is a predictable monthly fee that already bundles in what used to be several separate line items.

When modeling this side, include:

1. The monthly or annual subscription cost for the compute, storage, and networking resources you need
2. Any one-time migration costs
3. Savings from retiring hardware maintenance contracts
4. Savings from reduced internal labor hours previously spent on infrastructure upkeep
5. The value of high availability and compliance support built into the service, since this reduces the cost and staff time your organization would otherwise spend maintaining a highly available, compliant, and secure environment on its own

Step 3: Apply the ROI Formula

Once you have both sides mapped out, the ROI formula itself is simple:

ROI (%) = [(Total On-Prem Cost – Total IaaS Cost) / Total IaaS Cost] x 100

Run this over a three-year window at minimum, since that captures at least one hardware refresh cycle on the on-prem side and gives a close comparison. Many organizations also calculate a simple payback period, meaning how many months it takes for cumulative savings to exceed the migration cost.

Step 4: Account for the Value That’s not in a Spreadsheet

These still belong in your business case, even as qualitative points alongside the hard numbers:

1. Rapid deployment: The ability to quickly deploy new apps and services in response to market changes or customer demand, instead of waiting on procurement and provisioning timelines
2. Innovation capacity: Freedom to experiment with new technologies and business models without the risk and upfront cost of physical hardware
3. Collaboration: Infrastructure and applications accessible from anywhere, which supports remote work and distributed teams
4. Resource optimization: Visibility into resource utilization through monitoring tools, so you’re paying for what you actually use rather than guessing at future capacity needs
5. Regulatory support: Reduced burden of maintaining compliance on your own, since the provider’s facilities and processes are built around meeting regulatory requirements

For industries with strict compliance obligations, such as healthcare and financial services, this last point often shifts the ROI conversation from “can we save money” to “can we reduce risk while also saving money.”

Building the Business Case

When you present this to leadership, structure it in three parts: the true on-prem baseline, the IaaS cost model, and the resulting ROI and payback period, followed by the qualitative benefits that support long-term strategy. This framing helps the conversation move beyond a simple line-item comparison and into a discussion of total cost of ownership, risk, and where you want your IT team to spend its time.

Making the Switch with a Trusted Partner

Running the numbers is the first step. Choosing the right infrastructure partner is what determines whether those projected savings occur. Xigent’s fully managed IaaS is hosted in a secure, high-availability data center backed by SSAE 18/SOC II-compliant facilities, with monthly reporting so your team always has visibility into performance and costs.

Ready to calculate what switching to IaaS could mean for your organization? Contact Xigent today to build a customized ROI analysis based on your current environment.

Learn More about Xigent’s IaaS