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SAP S/4HANA conversion planner for SAP ECC

Describe your ECC 6.0 system once and get a recommended path (system conversion, new implementation or selective data transition) with the reasoning and the inputs that would flip it, a readiness score by area with the must-do prerequisites, a phase plan from an effort model you can edit line by line, a downtime estimate and a simplification item checklist for the modules you run. The support dates for ECC, S/4HANA releases and the private edition transition option are shown against your target go-live.

Every number is explained and editable. No prices are shown: SAP does not publish list prices for these offerings.

Describe your ECC system

Defaults are a mid-size example. Results update as you type.

Source system

System > Status, component SAP_APPL / EA-APPL, or SPAM.

More than one means a merge decision.

Required for conversion. Check in System > Status.

Must be split before conversion.

TB

Used for downtime, archiving and mock effort.

Modules in use
Tick every module with productive use
Custom code, interfaces, output, BW

Count from TADIR for customer namespaces.

%

From SCMON or UPL, over a full year if you can.

IDoc, RFC/BAPI, file, web service.

SAPscript, Smart Forms, Adobe.

Finance and master data
Add-ons and industry solutions

Installed namespaces from vendors (SAINT list).

Industry solutions and special components
Business goals
years

Beyond what an archive or read-only ECC could serve.

Team and dates
%

Share of time free from daily operations.

Recommended approach

Points from each input are listed below. Nothing is hidden.

Leads with a clear margin

System conversion (brownfield)

Convert the existing ECC system in place with the Software Update Manager. SUM migrates the database to SAP HANA if needed (database migration option, DMO), installs S/4HANA and converts the data to the new structures. History, configuration and custom code come along.

  • System conversion (brownfield)+5 pts
  • Selective data transition+1 pts
  • New implementation (greenfield)0 pts
Build the plan for

Why

  • +3System conversion: Processes and org structure stay broadly as they are: conversion keeps them with the least business change.
  • +2System conversion: 5 years of history must stay online: conversion keeps all of it in the same system.
  • +1Selective data transition: Selective data transition can keep chosen years of history.

What would flip it

  • If processes are redesigned, new implementation (greenfield) would lead.
  • If part of the business were carved out, selective data transition would lead.

Fits when

  • Processes and org structure are broadly right and the business wants continuity.
  • Full transaction history must stay online in the same system.
  • A fixed date (for example the end of 2027) leaves no room for a redesign.

Watch out

  • You also bring old design decisions and unused code unless you clean them up first.
  • Every mandatory prerequisite (CVI, Unicode, AS ABAP-only, add-on paths) must be finished before SUM runs.
  • Business downtime scales with data volume; plan data volume reduction and mock conversions.

Readiness: 78/100

Average of the areas below. A blocker stops the Software Update Manager regardless of the score.

  • Technical platform

    90

    Database is not SAP HANA: SUM with DMO migrates it during the conversion; HANA sizing is needed.

    • Run the Maintenance Planner early: it needs SPAM/SAINT patch 71 or higher.

  • Business Partner and CVI

    15

    Unsynchronized customers and vendors block the conversion.

    • Activate CVI and synchronize every customer and vendor to a Business Partner; clear synchronization errors (SAP Note 2265093).

  • Finance

    85

    FI-AR or SD credit management is replaced. Asset accounting data is migrated in the finance conversion.

    • Run the finance conversion in a development or test system first and transport the Customizing (SAP Note 2332030).
    • Close the period and keep reconciliation reports as audit evidence.
    • Plan the move to SAP Credit Management (SAP Note 2270544).

  • Logistics and replaced functions

    80

    Inventory moves to the simplified data model; custom stock reports need checking. SD data model, pricing and rebates change.

    • Work through the SI-Check items for your logistics modules.

  • Custom code

    81

    3,000 custom objects, about 1,500 in use.

    • Collect usage data (SCMON or UPL) for at least one full business cycle, including year-end, before deciding what to retire.
    • Run the Custom Code Migration checks (ATC, variant S4HANA_READINESS) against an S/4HANA check system (SAP Note 2241080).

  • Interfaces, output and BW

    74

    A separate BW system reads ECC extractors; check them against the extractor simplification items for your release.

    • Inventory every interface with its technology (IDoc, RFC, BAPI, file, web service) and owner; retest each one in every test cycle.

  • Data volume and quality

    90

  • Add-ons and industry solutions

    85

    3 third-party add-ons, 0 industry solution(s).

    • Ask every add-on vendor for its S/4HANA release and conversion path in writing; the Maintenance Planner blocks a conversion without one (SAP Note 2214409).

  • Team and timeline

    100

    Capacity 126 person-days per month; plan needs 992 person-days.

Phase plan: go-live Sep 2027

System conversion (brownfield). 992 person-days at 126 person-days per month.

Fits your target Apr 2028 with 7.6 months to spare

Months per phase = phase person-days / capacity, never below the phase minimum. Capacity = (6 internal FTE x 50% + 4 external FTE) x 18 days. Phases run in sequence here; overlapping preparation with assessment is a common way to gain time.

Phases at their minimum length: Assess, Prepare, Test and rehearse, Cutover. Adding people will not shorten those.

Work itemPerson-daysFormula
Assessment (Readiness Check, SI-Check, Maintenance Planner, usage data)2515 + 2 x 5 modules
Business Partner / CVI synchronization and data cleanup8080 (status: none) x 1 system(s)
Retire unused custom code301,500 unused objects x 0
Add-on clearance with vendors and retest243 add-ons x 8
Custom code remediation (ATC S4HANA_READINESS findings)3001,500 used objects x 40% affected x 0.5
Interfaces: adapt and retest8040 x 2
Output forms: retest on current technology1530 forms x 0.5
Finance conversion (GL, AA, CO, material ledger)4530 + 3 x 5 company codes
Move to SAP Credit Management2525
BW extractors and reports retest2525
Test cycles (integration, regression, UAT)1805 modules x 12 x 3 cycles
Mock conversions423 x (10 + 2 TB x 2)
Production cutover1515
Project management and quality overhead10612% of 886 person-days (spread over all phases)
Total992

Downtime and support dates

27.5 hours

(2 TB / 0.5 TB per hour + 10 h post-processing + 8 h validation) x (1 + 25% buffer)

  • The source is not on SAP HANA, so SUM runs the database migration option (DMO) inside the downtime unless you migrate to HANA beforehand.
  • Silent Data Migration (SDMI) moves some application data migration after go-live during business operations; it shortens downtime but adds load in the first days.
  • Measure the real throughput in a sandbox conversion on production-size data and replace the TB per hour assumption.
Model the window hour by hour

OKComputed go-live Sep 2027 is inside ECC mainstream maintenance (to end of 2027).

CheckYour target date itself is after end of 2027; any slip pushes further into extended maintenance.

ECC 6.0 (EHP 6 to 8) mainstream maintenance ends
Optional extended maintenance
Customer-specific maintenance
SAP ERP, private edition, transition option
S/4HANA 2023 mainstream maintenance (about seven years)
S/4HANA 2025 mainstream maintenance (about seven years)
S/4HANA: at least one release in maintenance until 2040
ECCS/4HANA on-premiseRISE private editionComputed go-live Sep 2027Your target Apr 2028Faded bars: derived dates, confirm in the SAP PAM.
Dates and conditions in detail

  • ECC 6.0 (EHP 6 to 8) mainstream maintenance ends: 2027-12-31

    SAP provides mainstream maintenance for SAP Business Suite 7 core applications, including SAP ERP 6.0, until the end of 2027.

    • The 2027 date applies to the latest three enhancement packages of SAP ERP 6.0. Systems on older EHPs should check their own dates in SAP Note 52505 and the SAP Release Strategy (login required).

  • Optional extended maintenance: 2028-01-01 to 2030-12-31

    Optional extended maintenance runs for three years, from the beginning of 2028 to the end of 2030, at a premium of two percentage points on the maintenance basis.

    • It must be contracted; it is not automatic.
    • Customers who do not take it move to customer-specific maintenance from 2028, where SAP still addresses known issues at unchanged fees.

  • Customer-specific maintenance: 2031-01-01 to 2031-12-31

    After extended maintenance ends, or for customers who did not take it, ECC moves to customer-specific maintenance. The scope is narrower than mainstream maintenance; read SAP Note 52505 for what it includes before relying on it.

    • Not a dated end: it continues, but without the deliveries of mainstream maintenance. Verify the scope with SAP.

  • SAP ERP, private edition, transition option: 2031-01-01 to 2033-12-31

    Business continuity for ECC from 2031 to 2033 for systems moved into SAP ERP, private edition under RISE with SAP. Services cover legal changes, security patches and bug fixing. SAP updated the page on 13 Oct 2026 to say subscriptions may run until 31 Dec 2035 with further prerequisites.

    • System migrated to SAP ERP, private edition on SAP HANA before 31 Dec 2030.
    • SAP HANA is the only supported database.
    • Minimum 2 TB for systems subscribed with the transition option.
    • Only available together with the max success plan during 2031 to 2033; its fee is additional.
    • Mitigation coverage needed for products not included (SAP Note 3591251).

  • S/4HANA 2023 mainstream maintenance (about seven years): 2023-10-01 to 2030-12-31derived, confirm in PAM

    S/4HANA 2023 (on-premise) shipped in October 2023 as the first release of a two-year cycle, with seven years of mainstream maintenance per release, up from five.

    • The end date shown is derived from the seven-year rule. Confirm the exact date in the SAP Product Availability Matrix.

  • S/4HANA 2025 mainstream maintenance (about seven years): 2025-10-01 to 2032-12-31derived, confirm in PAM

    S/4HANA 2025 is the next release in the two-year cycle; SAP publishes a Conversion Guide for SAP S/4HANA 2025 with its own restriction note (3549655) and release information note (3493301).

    • Release month and end of maintenance are derived from the two-year cycle and seven-year rule. Confirm both in the SAP Product Availability Matrix.

  • S/4HANA: at least one release in maintenance until 2040: 2040-12-31

    SAP commits that until 2040 there will always be at least one release of SAP S/4HANA in maintenance.

    • This is a product commitment, not the end date of any one release. Each release still needs upgrades to stay in maintenance.

Simplification checklist: 0/24 done

Filtered to your modules. Your SI-Check result is the authoritative list.

All conversions

FI (financial accounting)

CO (controlling)

FI-AA (asset accounting)

SD (sales and distribution)

MM (materials, inventory)

All the options, side by side

Including staying on ECC. Described factually; contract terms come from SAP or the provider.

  • System conversion (brownfield)

    Convert the existing ECC system in place with the Software Update Manager. SUM migrates the database to SAP HANA if needed (database migration option, DMO), installs S/4HANA and converts the data to the new structures. History, configuration and custom code come along.

    Fits when and watch-outs
    • Processes and org structure are broadly right and the business wants continuity.
    • Full transaction history must stay online in the same system.
    • A fixed date (for example the end of 2027) leaves no room for a redesign.
    • You also bring old design decisions and unused code unless you clean them up first.
    • Every mandatory prerequisite (CVI, Unicode, AS ABAP-only, add-on paths) must be finished before SUM runs.
    • Business downtime scales with data volume; plan data volume reduction and mock conversions.

  • New implementation (greenfield)

    Build a new S/4HANA system from SAP standard and migrate master data and open items, usually with a limited history. Processes are redesigned around current S/4HANA functions.

    Fits when and watch-outs
    • Processes, org structure or chart of accounts need a real redesign.
    • Most custom code is unused or replaceable by standard functions.
    • Several ECC systems are being consolidated into one.
    • Longer timeline and heavier business involvement in design and testing.
    • Historical data stays in ECC or an archive; plan read access for audit and tax retention.
    • Change management is a project of its own.

  • Selective data transition

    A middle path between conversion and rebuild: move selected configuration, code and data (for example chosen company codes or years) into S/4HANA, and leave obsolete data, such as data from divested company codes, behind.

    Fits when and watch-outs
    • Carve-outs, mergers or company code consolidation alongside the move.
    • You want to keep some processes and history but not all of it.
    • A clean core strategy for parts of the system.
    • Usually relies on specialized tools and services; scope and licensing need confirming with whoever provides them.
    • More complex cutover logic than either pure approach; test the selection rules early.

  • RISE with SAP, SAP Cloud ERP Private

    SAP's offer for moving on-premise ECC or S/4HANA into SAP Cloud ERP Private (formerly S/4HANA Cloud Private Edition), run in an SAP-managed cloud, bundled with tools and services. It is a commercial and operating model choice; the technical path (conversion, new implementation, selective) is still decided separately.

    Fits when and watch-outs
    • You want to hand over infrastructure and technical operations.
    • You want access to the transition option for ECC beyond 2030.
    • Subscription replaces license plus maintenance; compare total cost on the same scope and term.
    • Responsibilities between SAP, a hyperscaler and you are set by the contract; read the roles and responsibilities document.

  • Stay on ECC with SAP extended maintenance

    Keep ECC running to the end of 2030 under optional extended maintenance at two percentage points on top of the maintenance basis, then move.

    Fits when and watch-outs
    • You need time to finish CVI, data cleanup or a business redesign before the move.
    • Ends at the end of 2030 for on-premise ECC.
    • The premium applies to all support offerings.

  • Move ECC to SAP ERP, private edition, then convert

    Lift ECC onto SAP HANA in SAP ERP, private edition under RISE before the end of 2030 and use the transition option for business continuity from 2031 while the S/4HANA move completes.

    Fits when and watch-outs
    • Large systems (the offering has a 2 TB minimum) that cannot convert before 2030.
    • Requires the max success plan during 2031 to 2033 at an additional fee.
    • SAP HANA only. Pricing uplift depends on when you commit; see SAP's page.

  • Stay on ECC with third-party support

    Some companies keep ECC beyond SAP's dates with an independent support provider instead of SAP maintenance. It is a legitimate option for a stable system with no planned functional change; evaluate it on contract terms, not on marketing.

    Fits when and watch-outs
    • Stable processes, low regulatory change, and a deliberate decision to delay or skip S/4HANA.
    • No new SAP support packages, legal change deliveries or SAP Notes after SAP maintenance ends; ask the provider exactly how they cover tax and legal changes and security fixes.
    • Check what your SAP contract says about license rights to future releases and about returning to SAP maintenance later. Verify with SAP and your counsel.
    • Your landscape still ages: database, operating system and hardware support have their own end dates.

Next steps, export and review

Free, optional. Reopen it on any device.
Download plan:

An engineer who works on SAP conversions reads your plan and replies with the assumptions to challenge and the blockers to clear first.

  • Effort and downtime defaults are planning placeholders chosen to make the model readable, not industry benchmarks. Replace them with your own ATC, SI-Check and sandbox conversion results.
  • The simplification items here are the topics most conversions meet. The authoritative list for your system is the SI-Check result and the Simplification Item Catalog for your target release.
  • Support dates come from SAP public pages listed under Sources. Contract terms (extended maintenance, RISE, transition option) are set by your SAP agreement; confirm them with SAP.
  • No license, subscription or maintenance prices are shown: SAP does not publish list prices for these offerings.

How to use the S/4HANA conversion planner

  1. 1

    Describe the source system

    Enter the EHP level, database, Unicode status, company codes, plants and the modules in use. If you do not know a value, leave the default and note it as an open question: the readiness panel tells you which transaction or report gives the real answer.

  2. 2

    Add custom code, interfaces and data

    Use the Z object count from TADIR and the share of it actually executed in production (from usage data such as SCMON or UPL). Unused code is retired, not remediated, which is usually the largest single lever on effort.

  3. 3

    Answer the finance and master data questions

    Business Partner (CVI) status, classic or new GL, credit management, output technology and add-ons drive most of the pre-conversion work. They are the items that block the Software Update Manager if they are not finished.

  4. 4

    Set the team and the date

    Internal FTE, their availability and external FTE convert the effort model into months. Compare the computed go-live with the date you want and with the ECC maintenance dates on the timeline.

  5. 5

    Tune the assumptions, then export or save

    Every effort and downtime assumption is editable. Replace them with your own ATC, SI-Check and sandbox conversion results as they arrive, then export the plan to PDF, Excel or Word, or save it to your Netray account.

Questions

SAP ECC vs S/4HANA: what actually changes?

S/4HANA runs only on SAP HANA and simplifies the ECC data model: finance moves to the universal journal (ACDOCA), inventory to MATDOC, customers and vendors are maintained as Business Partners, credit management moves to SAP Credit Management and SD pricing to a new table. Some functions are replaced, for example SD Foreign Trade by SAP GTS and SD rebates by Settlement Management. The Simplification Item Catalog lists every change per release.

When does SAP ECC support end?

Mainstream maintenance for SAP ERP 6.0 (the latest three enhancement packages) ends at the end of 2027. Optional extended maintenance runs from 2028 to the end of 2030 at two percentage points on top of the maintenance basis. After that, or without extended maintenance, ECC moves to customer-specific maintenance. Systems moved to SAP ERP, private edition under RISE can use a transition option from 2031 to 2033, which SAP has since said may run to the end of 2035 with further prerequisites.

Brownfield or greenfield: how does the planner decide?

It scores system conversion, new implementation and selective data transition on the inputs that matter most: whether processes stay or are redesigned, how much custom code is used, how much history must stay online, organizational change such as carve-outs or consolidation, data quality, data volume and the time left before your date. The reasoning is listed line by line, and the planner tests which single change to your inputs would change the recommendation.

What must be done before the Software Update Manager can run?

The system must be Unicode and AS ABAP-only, the start release must be supported by the target release's restriction note, CVI must be complete so every customer and vendor is a Business Partner, the Maintenance Planner must find a path for every add-on, business function and industry solution, and the SI-Check must show no errors at return code 8 or higher before downtime.

Do we need to be on SAP HANA before converting?

No. If the database is not SAP HANA, the database migration option (DMO) of SUM migrates it to HANA during the conversion. Planning still needs HANA sizing, and data volume reduction pays off twice: shorter downtime and a smaller HANA system.

How is the downtime estimate calculated?

Downtime hours = data volume in TB divided by migration throughput in TB per hour, plus post-processing hours, plus business validation hours, plus a buffer percentage. All four values are editable. The throughput default is a placeholder: measure it in your sandbox and mock conversions, then replace it. Downtime-optimized conversion moves part of the data conversion into uptime.

Is RISE with SAP the same as converting to S/4HANA?

No. RISE is a subscription and operating model: SAP Cloud ERP Private runs in an SAP-managed cloud with bundled tools and services. You still choose a technical path (conversion, new implementation or selective data transition). Compare it with on-premise S/4HANA on the same scope, term and responsibilities.

Is staying on ECC with third-party support a real option?

It can be for a stable system with little functional or regulatory change. The trade-offs are that SAP stops delivering support packages, legal changes and notes for your system, and your contract may limit rights to future releases or the cost of returning to SAP support. Read the contract and get written answers on tax, legal and security coverage before deciding.

Is my data sent anywhere?

No. The planner runs in your browser. Data is stored only if you save it to your Netray account, and sent to us only if you ask an engineer to review the plan.

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Sources

Support dates, conversion prerequisites and SAP Note references were checked against these pages on 2026-10-22. Contract terms come from your SAP agreement; release dates marked derived must be confirmed in the SAP Product Availability Matrix.