SAP Readiness Check has long been the go-to tool for evaluating the compatibility and requirements of SAP systems before a transition to S/4HANA. In its latest update (October 2025), it now also provides total time estimates—covering both overall project duration and downtime during the conversion.
Planned Downtime Calculator
Downtime Estimation: The tool offers a Planned Downtime Calculator that estimates the duration of the business downtime required for the system conversion.Phased Breakdown: It displays default durations for each conversion phase—data import, software update, post steps—based on empirical values from past projects.Best Practice Advisory: Users can choose a standard conversion (typical data center) or a downtime-optimized path (available since SUM 2.0 SP10) to reduce disruption.Tip to Reduce Downtime: Encourages pre-conversion archiving and housekeeping. [help.sap.com], [help.sap.com]
Here’s format used:
Total Downtime: xx hours xx minutes
Phases
Default Value
Your Value
System Ramp-Down
Typically, this phase includes the completion of the normal workload and the isolation of the system. For example, it includes logging out end users, stopping background processes, and clearing delta queues.
xh
Downtime Preparations
This phase usually includes the extraction of preconversion data for later reconciliation (data validation). In addition, it includes several last conversion-relevant preparation steps for applications. The scope depends on the functional usage of the system.
x h
Technical Downtime (SUM)
This phase includes the database migration, the software upgrade, and the data conversion.
xx h
Technical Postprocessing and Data Conversion Preparation
Typically, this phase includes adjustments of the technical infrastructure, postprocessing steps after the technical conversion, and customer transports, including customizing for FI conversion and the implementation of relevant SAP Notes.
x h
Finance and Material Ledger Data Conversion
In this phase, the financial data (FI, FI-GL, FI-AA, CO, and ML) is migrated into the universal journal table ACDOCA
x h (estimated)
7 h (empirical)
Empirical value for medium-sized systems
Business Validation
Usually, this phase includes tests that are performed by the key users to ensure that the system works as expected from a functional perspective.
x h
Go/No-Go Decision
In this phase, the project management team holds a final status meeting and makes the go/no-go decision, based on the results of the reconciliation and the functional tests.
xx min
System Ramp-Up
In this phase, normal system operations are resumed.
2 h
Fallback Buffer
This phase includes a fallback buffer that is required if the conversion was not successful.
3 h
SAP Readiness Check has long been the go-to tool for evaluating the compatibility and requirements of SAP systems before a transition to S/4HANA. In its latest update (October 2025), it now also provides total time estimates—covering both overall project duration and downtime during the conversion. Planned Downtime CalculatorDowntime Estimation: The tool offers a Planned Downtime Calculator that estimates the duration of the business downtime required for the system conversion.Phased Breakdown: It displays default durations for each conversion phase—data import, software update, post steps—based on empirical values from past projects.Best Practice Advisory: Users can choose a standard conversion (typical data center) or a downtime-optimized path (available since SUM 2.0 SP10) to reduce disruption.Tip to Reduce Downtime: Encourages pre-conversion archiving and housekeeping. [help.sap.com], [help.sap.com]Here’s format used:Total Downtime: xx hours xx minutesPhasesDefault ValueYour ValueSystem Ramp-DownTypically, this phase includes the completion of the normal workload and the isolation of the system. For example, it includes logging out end users, stopping background processes, and clearing delta queues.xh Downtime PreparationsThis phase usually includes the extraction of preconversion data for later reconciliation (data validation). In addition, it includes several last conversion-relevant preparation steps for applications. The scope depends on the functional usage of the system.x h Technical Downtime (SUM)This phase includes the database migration, the software upgrade, and the data conversion.xx h Technical Postprocessing and Data Conversion PreparationTypically, this phase includes adjustments of the technical infrastructure, postprocessing steps after the technical conversion, and customer transports, including customizing for FI conversion and the implementation of relevant SAP Notes.x h Finance and Material Ledger Data ConversionIn this phase, the financial data (FI, FI-GL, FI-AA, CO, and ML) is migrated into the universal journal table ACDOCAx h (estimated)7 h (empirical) Empirical value for medium-sized systems Business ValidationUsually, this phase includes tests that are performed by the key users to ensure that the system works as expected from a functional perspective.x h Go/No-Go DecisionIn this phase, the project management team holds a final status meeting and makes the go/no-go decision, based on the results of the reconciliation and the functional tests.xx min System Ramp-UpIn this phase, normal system operations are resumed.2 h Fallback BufferThis phase includes a fallback buffer that is required if the conversion was not successful.3 h Read More Technology Blog Posts by Members articles
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