SAP S/4HANA Migration: Cost, Timeline & a Step-by-Step Plan
With mainstream support for SAP ECC ending in 2027, S/4HANA is no longer optional. Here is how the migration paths compare, what really drives cost and timeline, and a step-by-step plan to get there safely.
- SAP S/4HANA migration is a deadline-driven project: mainstream maintenance for SAP ECC ends in 2027, so most enterprises need a credible plan in motion well before then.
- There are three routes - a brownfield system conversion, a greenfield reimplementation, or a selective (bluefield) transition - and the right one depends on how much of your current setup is worth keeping.
- Cost and timeline are driven by system size, custom code, data quality and integrations, not a fixed price, which is why every serious move starts with a readiness assessment.
- Data cleanup and custom-code remediation are the long poles of the project - starting them early is the single biggest lever on both budget and schedule.
SAP S/4HANA migration is the move from legacy SAP ECC to SAP's current ERP suite, and with mainstream support for SAP ECC ending in 2027 it is no longer a question of if, but when and how. There are three ways to get there: a brownfield system conversion that migrates your existing system in place, a greenfield reimplementation that rebuilds on best practice, and a selective (bluefield) transition that blends the two. Cost and timeline are not fixed - they are driven by system size, custom code, data quality and integrations, so any credible number starts with a readiness assessment rather than a price list. This guide explains the paths, the factors that move budget and schedule, the common mistakes to avoid, and a step-by-step plan to de-risk the move.
What SAP S/4HANA Migration Actually Means
SAP S/4HANA migration is the transition of your ERP from the older SAP ECC (Business Suite) platform onto S/4HANA, SAP's current-generation suite built on the in-memory HANA database. It is more than a version upgrade: the underlying data model is simplified, the SAP GUI gives way to the role-based Fiori experience, and the platform becomes the foundation for SAP's cloud, AI and clean-core roadmap.
Because the data model and custom-code rules change, most organisations treat it as a transformation project with a defined path, not a patch. How you make the move - convert in place, rebuild clean, or migrate selectively - shapes the cost, the timeline and how much of your current setup carries forward.
Why Move to S/4HANA Now
The 2027 support deadline is the headline reason to act, but putting the move off also shortens your runway and pushes you into a crowded market for SAP talent later. The upside is real beyond the deadline:
- Mainstream maintenance for most SAP ECC releases ends in 2027, with extended support after that at a premium.
- S/4HANA runs on the in-memory HANA database, enabling real-time reporting and a simpler data model.
- The Fiori user experience replaces dated SAP GUI screens with modern, role-based apps.
- It is the foundation for SAP's cloud roadmap, AI features and clean-core extensibility.
- Starting early means a calmer timeline, better talent availability, and time to clean up data and custom code.
Treat 2027 as a planning horizon, not a finish line. Readiness assessments, data cleanup and custom-code remediation are the long poles - start them early.
Brownfield, Greenfield or Selective: The Three Migration Paths
How you get to S/4HANA matters as much as getting there. The three approaches trade off speed, cost and how much of a fresh start you get:
| Path | Best For | What Happens |
|---|---|---|
| Brownfield (system conversion) | Stable processes worth keeping | Convert the existing system in place, retaining config, data and history |
| Greenfield (new implementation) | Outdated processes, fresh start | Build a clean S/4HANA system and re-engineer processes from best practice |
| Selective / bluefield | Large landscapes, mixed needs | Migrate selected data, processes and code into a new system on your terms |
There is no universally right path. Brownfield is usually faster and cheaper; greenfield buys you a clean core and modern processes; selective splits the difference for complex landscapes.
Which Path Fits: A Decision Framework
The right path follows from the state of your current system and your appetite for change. Use this matrix to narrow the choice before a formal assessment confirms it:
| If your situation is... | Lean toward | Because |
|---|---|---|
| Processes work well, low custom-code debt | Brownfield | Converting in place is the lowest-effort route and preserves history |
| Processes are dated, heavy legacy customisation | Greenfield | A clean rebuild removes technical debt and adopts standard best practice |
| Large multi-entity landscape, uneven maturity | Selective / bluefield | You migrate the good parts and rebuild the rest on your own terms |
| Tight deadline, limited change appetite | Brownfield | Fewer moving parts and less process re-engineering to test and adopt |
| Merger, carve-out or major reorganisation | Greenfield or selective | Structural change is easier to model in a fresh system than to convert |
What Drives the Cost and Timeline
Anyone who quotes a fixed S/4HANA price before seeing your system is guessing. Both cost and timeline are driven by a handful of factors that vary enormously between businesses - these are the levers, expressed as relative effort rather than invented figures:
- System size and data volume - more data means longer migration and cleanup.
- Custom code (Z-code) - every custom program needs to be assessed, adapted or retired for S/4HANA compatibility.
- Number and complexity of integrations - interfaces to banks, CRMs, warehouses and third parties all add work.
- Data quality - duplicate, stale or inconsistent master data slows everything down and is best fixed before you move.
- Deployment target - public cloud, private cloud (RISE with SAP) or on-premise each carry different effort and cost shapes.
- Process change - the more you re-engineer versus convert, the more testing and change management you take on.
A Step-by-Step S/4HANA Migration Plan
A successful migration is a sequence of de-risking steps, not a big-bang switch. This is the path we follow:
- Readiness assessment - run SAP Readiness Check, inventory custom code and integrations, and pick the right path.
- Business case and scope - agree the deployment model, processes in scope, and a phased timeline.
- Data cleanup and archiving - fix master data and archive what you do not need to carry over.
- Custom-code remediation - adapt or retire Z-code, moving toward a clean core with side-by-side extensions.
- Build and convert in a sandbox - stand up the S/4HANA system and run a trial conversion.
- Test thoroughly - functional, integration, performance and user-acceptance testing across cycles.
- Cutover and go-live - a planned, rehearsed cutover with a clear rollback option.
- Hypercare and optimise - intensive post-go-live support, then ongoing improvement and Fiori rollout.
The assessment and cleanup steps look unglamorous but decide the project. Rushing them is where timelines slip and budgets overrun.
Not Sure Which Path Fits Your SAP Landscape?
We will run a readiness assessment of your current system - custom code, data and integrations - and come back with a recommended path and a realistic, phased plan. No fixed quote before we understand your system.
Deployment Targets Compared
Where S/4HANA runs shapes both effort and ongoing cost. There is no single best target - it follows from your IT strategy, compliance needs and appetite for managing infrastructure:
| Target | Best For | Trade-off |
|---|---|---|
| Public cloud (SaaS) | Standardised processes, fast adoption | Least infrastructure to manage, least customisation freedom |
| Private cloud (RISE with SAP) | Enterprises wanting cloud with control | Managed landscape with more flexibility than public cloud |
| On-premise | Strict data-residency or bespoke needs | Maximum control, but you own the infrastructure and upgrades |
Common Mistakes to Avoid
Most S/4HANA overruns trace back to a short list of avoidable errors, generalised from how these projects typically go wrong:
- Carrying over years of unused custom code instead of cleaning the core.
- Underestimating data cleanup - it is almost always bigger than expected.
- Leaving testing and change management to the end rather than running them throughout.
- Treating it as a pure IT project rather than a business transformation with process owners engaged.
- Starting too late and paying a premium for scarce talent near the deadline.
- Expecting a fixed price before anyone has assessed the system, then being surprised by scope.
How Acqurio Tech Approaches S/4HANA Migration
We help mid-market and enterprise teams plan and deliver S/4HANA migrations without the disruption, delivered remotely from India with an engineered overlap window for close collaboration:
- SAP development and migration - readiness assessment, path selection and end-to-end delivery.
- Hire SAP consultants - pre-vetted SAP talent to extend your team for the project.
- Enterprise software development - clean-core extensions and integrations around SAP.
- Cloud and DevOps - the infrastructure and pipelines for a cloud S/4HANA landscape.
Conclusion
S/4HANA migration is a deadline-driven transformation, not a routine upgrade. The teams that come out ahead start early, choose the path that matches how much of their setup is worth keeping, and treat data cleanup and custom-code remediation as the real work. Begin with a readiness assessment, phase the rollout, and the 2027 deadline becomes a plan rather than a panic. If you want a second opinion on your path, talk to our SAP team.
Frequently asked questions
How do you plan an SAP S/4HANA migration and pick the right path?
Start with a readiness assessment: run SAP Readiness Check, inventory custom code and integrations, and gauge data quality. That tells you whether a brownfield conversion, a greenfield rebuild or a selective transition fits, and feeds a phased plan. The right path depends on how much of your current setup is worth keeping and your appetite for process change.
When does support for SAP ECC end?
Mainstream maintenance for most SAP ECC (Business Suite 7) releases ends in 2027, with extended support available afterwards at additional cost. That makes a credible S/4HANA plan a priority for most SAP customers well before then.
What is the difference between brownfield and greenfield S/4HANA migration?
Brownfield (system conversion) migrates your existing system in place, keeping configuration, data and history - it is usually faster and cheaper. Greenfield builds a brand-new system and re-engineers processes from best practice, which is more effort but gives you a clean core. A selective or bluefield approach blends the two.
How long does an S/4HANA migration take?
It depends on system size, custom code, data quality and how much process change you take on. A focused brownfield conversion is much quicker than a full greenfield reimplementation. A readiness assessment is the fastest way to get a realistic timeline for your landscape.
How much does S/4HANA migration cost?
There is no fixed price - cost is driven by data volume, custom code, integrations, deployment model and the degree of process change. We do not quote a number before assessing your system; a readiness assessment produces a tailored estimate rather than a guess.
Do we have to move to the cloud?
No. S/4HANA can run on public cloud, private cloud (including RISE with SAP) or on-premise. The right target depends on your IT strategy, compliance needs and appetite for managing infrastructure.
What happens to our custom ABAP code?
Every custom program is assessed for S/4HANA compatibility, then adapted, replaced with standard functionality, or retired. Moving custom logic to side-by-side extensions keeps the core clean and makes future upgrades far easier.
Can we keep running during the migration?
Yes. A well-planned migration uses sandbox builds, multiple test cycles and a rehearsed cutover with a rollback option, so your live operations keep running until a planned go-live.