“How much will S/4HANA cost?” has no single answer — a straightforward mid-market conversion and a multi-country global rollout are entirely different programmes. What can be answered is what drives the cost, how long programmes really take, and why 2026 makes both harder. This article is part of our complete SAP ECC to S/4HANA migration guide.
The main cost drivers
- Landscape size: company codes, countries, plants and the number of connected systems.
- Custom code: how much exists, how much is used, and how deeply it touches simplified areas.
- Data quality: the cleansing and harmonisation needed before loading.
- Approach: greenfield, brownfield or selective transition, each with different effort profiles.
- Integrations and testing: interfaces, regression testing and business sign-off.
- Licensing and hosting: including whether you move through RISE or GROW with SAP.
- Change management: training and process change, which is often under-budgeted.
Realistic timelines
Typical programmes run 18 to 36 months. With mainstream maintenance for ECC ending on 31 December 2027, organisations starting late in 2026 face compressed schedules — or a bridge through extended maintenance to 2030 at a premium. See the SAP 2027 deadline explained.
Why programmes overrun
Industry research consistently finds overruns are common: SAPinsider’s 2026 research reports that many organisations already live on S/4HANA spent more than they originally budgeted. The usual causes are predictable — custom code and data work discovered late, scope creep, testing compressed at the end, and specialist resources arriving later than planned.
The cheapest S/4HANA programme is the one that is sized properly before it starts.
ESS ENN Associates Enterprise Solutions Team
The talent squeeze
Thousands of organisations are competing for the same pool of SAP specialists before the deadline, and industry commentators report that consulting rates have risen sharply in 2026 as a result. Locking in capacity early, and making the best use of scarce experts, is now a cost lever in its own right.
How to control cost
- Assess first: size custom code, data and process gaps with evidence before committing to a budget.
- Retire before you migrate: unused code, obsolete data and redundant interfaces cost money to move.
- Choose the right approach: compare greenfield, brownfield and bluefield on your own estate.
- Use AI where it is strong: assessment, code remediation, data cleansing and test generation.
- Test early and often: continuous testing is far cheaper than a late, compressed test phase.
For licensing options, see RISE with SAP vs GROW with SAP; for smaller organisations, S/4HANA for the mid-market.
ESS ENN Associates supports SAP S/4HANA programmes with AI-assisted assessment, custom-code and data remediation, and testing, through our AI agent development, data engineering and legacy modernisation teams. For an evidence-based estimate of your programme, Contact us.