SAP S/4HANA Migration Timelines: The Average, the Range, and the Factors Behind Both

The typical SAP S/4HANA migration takes 15 to 20 months, and the ones that run longer share one trait: they carry more change across.

Two user-group surveys and SAPinsider’s own benchmark research agree on the center of that range and on what pushes a project toward either edge. That figure now decides the 2027 planning question. Mainstream maintenance for SAP ERP 6.0 ends at the close of next year, so a company that has not started needs to know whether an average project fits in the time left, and what to do if it does not.

The Benchmarks Point to Roughly a Year and a Half

ASUG’s 2026 research, based on 194 members, found the average go-live takes about 1.4 years. Approach makes a measurable difference: brownfield conversions, chosen by 47% of respondents, averaged 15.8 months, while greenfield implementations averaged 20.2 months. ASUG’s 2024 survey of 208 members set the outer bounds, with projects ranging from four months to six years around a 1.5-year average.

SAPinsider’s Deployment Approaches to SAP S/4HANA research, published in July 2025, shows the same center with a widening spread. The 2024 data put the average deployment at around 18 months. In 2025 the distribution split: a quarter of respondents expected their deployment to take more than two years, excluding the business case, while 13% expected to finish in under six months. Robert Holland, SAPinsider’s chief research officer, attributes the short end to rapid conversions and the long end to older, heavily customized SAP ECC systems.

Scope Sets the Length of the Project

The factors that stretch a timeline are consistent across surveys, and nearly all concern what the company brings across.

SAPinsider’s 2025 respondents named the complexity of the existing data landscape (56%), custom code that must be replaced or re-engineered (49%), and data harmonization and cleansing (44%) as the biggest factors. ASUG’s 2026 respondents who missed their dates cited business changes (55%), unexpected complexity (45%), and scope creep (42%).

The response has been to narrow scope. In 2025, 55% of SAPinsider respondents said they would move to SAP S/4HANA as quickly as possible instead of as part of a broader transformation, and system conversions rose to 49% of planned deployments. A conversion is faster because it brings the existing environment across as it stands, and it defers custom-code remediation, process standardization, and data cleanup until after go-live. Holland cautions that those tasks still have to happen and can cost more once the system is live.

Staffing is the other constraint. Only 12% of SAPinsider’s 2025 respondents planned to rely on internal teams alone, and with 20,000 to 25,000 customers yet to license SAP S/4HANA, SAPinsider expects partner capacity to tighten through 2027 and beyond.

What the Timeline Means for the 2027 Date

A project of average length that starts now finishes in early 2028, after mainstream maintenance has ended.

SAPinsider’s ERP Migration and Transformation 2026 report, based on 296 respondents surveyed between December 2025 and March 2026, found 35% planning to switch before the end of 2026 and called that optimistic for any organization not already underway. Its conclusion is direct: projects in progress will most likely finish before the end of 2027; those still building a business case most likely will not.

Extended maintenance through 2030 and the transition option to 2033 are therefore planning instruments for much of the remaining SAP ECC base, with their conditions covered in SAPinsider’s earlier pieces on the support deadlines and what SAP supports after 2027. The practical exercise is to estimate the project from the landscape, fix the scope, and read off which bridge the dates require.

What This Means for SAPinsiders

Estimate from your own landscape. Count the custom objects, data sources, and integrations that will move before setting a date. That figure is the one the budget and partner contract should reflect.

Decide scope before choosing a partner. A conversion and a redesign are different projects with different durations and skills. Fixing scope first makes partner proposals comparable.

Treat 2030 as the planning floor if work has not started. An average project beginning now ends after mainstream maintenance. Budgeting extended maintenance today turns a forced decision in late 2027 into a planned one.