SAP ECC to S/4HANA Migration Cost and Timeline: 2026 Breakdown vs ERPNext

The first S/4HANA number most ECC customers see covers two things: the subscription and the integrator's fee. A complete budget has nine lines. The seven that are missing are where projects go over.

This guide is for CFOs, CIOs and IT heads who have to put a number in front of a board. It gives published benchmarks for each line, planned and actual timelines, and a worked five-year comparison with ERPNext for a 250-user manufacturer.

One disclosure first. We are Sanskar Technolab, an ERPNext implementation partner. The S/4HANA figures here come from named third-party benchmarks. The ERPNext figures are our own published ranges. We have said where the comparison flatters us.

What S/4HANA migration costs by company size

The most useful public benchmark we found is from VendorBenchmark, which draws on more than 80 enterprise migrations completed between 2023 and 2025. It bands cost by the number of SAP users and by complexity. "Standard to moderate" means limited to moderate custom code and up to about 50 interfaces. "Complex" means heavy customisation and more than 50 interfaces.

A second source generally concurs with this conclusion, which was also made by LeverX, an SAP partner. In September 2026, LeverX issued the following tabulations of costs for ventures in the USA: for a small and not too complicated conversion $750,000-$1.5 million; for a middle-sized brownfield undertaking $1.5-$4 million; for an enterprise transformation $4-$10 million; and for a substantial project spread across the world $10-$25 million.

At the very top, the numbers appear in public accounts. Halliburton reported $154 million of "SAP S4 upgrade expense" in 2025, after $124 million in 2024.

These are project costs, including internal resources. The ongoing subscription or licence is a separate line, and it does not end at go-live.

The nine lines in a complete budget

You should request every point separately. If any individual point does not come back, it has not been eliminated. It has just been shifted towards your domain.

Then add contingency. Tachyon recommends 15 to 20% for mid-market migrations.

Why custom code decides the bill

Custom code is the largest single line in that sample, and the estimates for it vary more than for any other line. LeverX's sample puts it at 17% of the budget. Redress Compliance says Z-code remediation typically runs to 40 to 60% of total migration cost. Tachyon describes fewer than 500 custom objects as a minor cost and 5,000 or more as months of remediation work.

The spread exists because custom code is where your business lives in ECC. A pricing rule, a dispatch sequence, a quality hold, an approval chain: each one was written in ABAP because standard SAP did not do what you needed. On the way to S/4HANA, every one of those objects has to be checked against the new data model. Under SAP's "clean core" approach, logic you want to keep is moved out of the core and rebuilt as an extension.

So a large part of an S/4HANA budget pays for moving your own workflows into a new extension model that SAP defines and SAP can change. This is the point at which the cost question becomes a control question. If you are going to pay to rebuild those workflows, you can choose where they are rebuilt.

On ERPNext they are rebuilt in Python and JavaScript on the open-source Frappe Framework. The code is yours. Your own developers can read it and change it, and no vendor release calendar sits between you and the next change. The licence saving matters too, but for most enterprise buyers it comes second to that.

One practical step applies whichever route you take. Before you ask for any quote, run usage logging on ECC across a full month-end. The count of custom objects that are still executed is often well below the count that exists, and it is the number every quote should be based on.

How long it takes: planned against actual

Plans and outcomes differ enough that you should budget on the outcome. VendorBenchmark reports both.

Horváth's 2025 study of 200 companies points the same way. Projects took 30% longer than planned on average. Fewer than one in ten completed transformations kept to schedule. A quarter exceeded budget heavily and another 40% strongly, and 65% reported strong or very strong quality deficits in the result.

The causes respondents gave were not technical: scope added during the project, weak project management, underestimated testing and data migration, and slow decisions. Those risks apply to an ERPNext project as well, which is why we have applied the same 30% to our own range in the table.

Timing now carries a cost of its own. A mid-size brownfield project started in October 2026 and delivered in 14 to 20 months finishes between December 2027 and June 2028. Mainstream maintenance for ECC ends on 31 December 2027, so most such projects should budget for at least a year of extended maintenance. Our guide to every SAP ECC deadline sets out the dates and conditions.

Worked example: 250 users, S/4HANA against ERPNext

Consider an organization that has three factories and 250 users on ECC 6.0, operating FI, CO, MM, SD and PP and has around 400 Z-programs. There are 40 advanced users, 110 core users and 100 self-service users, resulting in 66 FUE.

Route A is a brownfield conversion to S/4HANA private cloud under RISE. Route B is a replacement with ERPNext. Both are costed over five years, with the same 20% contingency on the project.

On these figures the ERPNext route costs roughly a tenth of the S/4HANA route over five years. The gap after year five is wider, because the subscription continues and the ERPNext project cost does not repeat.

What the comparison leaves out

A tenfold gap deserves suspicion. Here is where it comes from, and where it could narrow.

Part of the gap is geography.

Our delivery team is in India. The S/4HANA benchmarks reflect mostly US and European integrator rates of $1,600 to $3,600 a day for a consultant at specialist and top-tier firms. VendorBenchmark puts the saving from offshore-led S/4HANA delivery at 35 to 55% of consulting fees, with timelines 15 to 25% longer. That narrows the project line. It does not touch the subscription line.

Our figures are published ranges, not a quote.

We used the enterprise band from our ERPNext implementation cost guide. An ECC replacement with heavy ABAP logic and many years of history is priced after an assessment and can exceed the top of that band.

It still holds under stress.

If our project cost came in at three times the top of the band, the ERPNext five-year total would be about $864,000. That is still under half the low end of the S/4HANA range.

Neither column includes everything.

Your internal team's time, ECC maintenance paid during dual running, and licences for third-party tools are left out on both sides.

There may be a small overlap.

VendorBenchmark's project band includes some licensing increments. If you remove the first year of subscription to allow for that, the S/4HANA range becomes about $1.66 million to $3.78 million.

The S/4HANA subscription uses opening prices.

A well-negotiated deal lands lower. At $190 per FUE, the five-year subscription for 66 FUE is about $752,000.

Cost is not all the consideration as well. It is a worthy purchase in situations where you use SAP industry solutions, payroll in multiple countries in SAP, operate in a conglomerate that requires SAP, or have an ongoing program at work. Then, the proper comparison would be between S/4HANA pricing and not different products. For other options within the market, visit our guide to SAP S/4HANA alternatives.

Eight questions to put to every quote

These apply to an S/4HANA quote. Questions four to seven apply just as much to an ERPNext quote, including ours.