A realistic SAP S/4HANA migration timeline, and what makes it longer

A mid-market S/4HANA migration typically runs 6 to 18 months. The single biggest cause of delay is data, with projects averaging about 30 percent longer than planned.

A mid-market S/4HANA migration typically runs 6 to 18 months. Large enterprises run 18 to 36. The single biggest cause of delay is data, and discovery and cleansing alone consume about 40 percent of a healthy timeline.

• 40% of the migration timeline is discovery and data cleansing. Pre-move cleansing with validation rules cuts post-migration defects by about 60% and post-go-live performance issues by about 25%. The work you skip up front returns as production incidents.

What drives the timeline

Data volume, the number of customizations, and how clean the master data is. A company with governed data and little custom code moves fast. One with sixteen years of ungoverned data and a thicket of custom code does not. The platform conversion is the predictable part. The data work is the variable that decides whether you land at 8 months or 18.

Why projects slip

A 2025 Horvath study of 200 SAP customers found only 8 percent finished on time, with projects running about 30 percent longer than planned. Across the broader 2026 survey set, 60 percent run long and 55 percent go over budget. The named culprits are underestimated testing and data migration, the data work that nobody scoped properly.

How SAP programs miss

The same survey set, the same story: the slip is in quality and data, not the technical cutover.

• Missed quality targets
• Planning overruns (avg 30% longer)
• Exceeded budget

Source: SAP migration outcome surveys, 2026.

How to protect your timeline

Measure readiness before you commit to a go-live date, so the plan is real. Remediate the data before cutover. Keep the data workstream off the critical path by staffing it senior. A four-week Blueprint up front is the cheapest insurance against a six-month slip, and automated migration tooling can recover around three months on top of it.

Where the installed base is, early 2026

Most of the market is already moving. The remaining third competes for the same scarce specialists.

• Fully or partially live on S/4HANA
• Large enterprises still in planning or exploration
• Migration projects running late or over budget

Source: Precisely/ASUG and PAC migration surveys, 2026.

Starting matters too. By early 2026, 59 percent of companies were already live or in process, so the bench you need is filling up. The 30-day Analytics Truth Audit gets you a real timeline before you commit to a date.

Frequently asked questions

How long does an S/4HANA migration take?

Typically 6 to 18 months for the mid-market and 18 to 36 months for large enterprises, depending on data volume, customization, and how clean the data is.

Why do migrations run long?

A 2025 Horvath study found only 8 percent of projects finished on time, with projects running about 30 percent longer than planned. Underestimated testing and data migration are the main causes.

What makes one migration faster than another?

Clean, governed data and little custom code. Both shorten the timeline dramatically. Ungoverned data and heavy customization extend it.

Can we shorten the timeline?

Yes, by measuring readiness before committing, remediating data before cutover, and keeping the data workstream senior and off the critical path.

Does a Blueprint add time?

It saves time. A four-week Blueprint up front prevents the mid-program revisions and data surprises that cause the largest delays.

When should we start?

Now. Mainstream ECC maintenance ends December 2027, and starting late compresses the timeline into a crowded, expensive window.