European Multi-Utility: How We Cut S/4HANA Conversion FUE Count by 40% Against SAP's Initial Sizing

The Situation

The utility had run on SAP ECC 6.0 EHP8 for more than a decade, with a heavily customised IS-U (Industry Solution for Utilities) implementation supporting customer billing, meter-to-cash, and asset management for the three commodities. The Business Suite 7 mainstream maintenance deadline at the end of 2027 forced a conversion decision. The board selected S/4HANA, on-premise initially with a planned move to Cloud ERP Private at next renewal. The conversion business case had been approved on a budget that assumed broadly flat licensing economics through the transition.

SAP's sizing exercise, conducted by the SAP account team and a partner integrator, produced an FUE count that did not match the budget assumption. The proposed FUE conversion mapped every named ECC Professional user to a Functional or Productivity FUE block, applied an aggressive ratio that did not reflect actual usage patterns, and added a Compatibility Pack risk overlay covering legacy IS-U functions for a transitional period. The proposed FUE count came in 60 to 80 percent above the internal benchmark. The licensing uplift threatened the conversion business case.

The utility's CIO refused to accept the sizing without challenge. Procurement was instructed to commission an independent FUE rebuild before signing the conversion Order Form. We were retained to lead the work, with a brief to validate or rebut SAP's sizing, neutralise the Compatibility Pack risk, and protect the conversion timeline.

What We Did

1. Rebuilt the user inventory from STAR and SLAW. We pulled three years of transaction history from STAR, classified every user against the SAP-published transaction code maps for Professional, Functional, Productivity, and Developer FUE categories, and overlaid the results onto HR records to confirm role accuracy. The exercise identified that roughly 35 percent of users SAP had categorised as Professional met the contractual test for Functional or Productivity FUE, where the unit cost is materially lower.
2. Applied the actual FUE conversion ratios. SAP publishes FUE conversion ratios that translate Named User Professional licences into FUE equivalents at specified rates. We applied the ratios precisely, not generously. We separated continuing users from contract staff and infrequent users, and we applied the test of the SAP price list rather than the integrator-suggested allocation. The recalculated FUE count came in below SAP's proposal across every user category.
3. Neutralised the Compatibility Pack risk. SAP's sizing applied a Compatibility Pack overlay that captured legacy IS-U functionality SAP planned to deprecate during the transition window. The overlay added FUE that the utility would have paid for but never structurally needed. We worked with the technical team to map exactly which legacy transactions would persist past the conversion go-live, negotiated a contractual extension of the Compatibility Pack at no additional FUE cost, and removed the speculative overlay from the sizing.
4. Pushed back on the Functional FUE allocation. SAP's sizing had defaulted call-centre and operations staff to Functional FUE at the upper allowable ratio. The actual transaction profile for these users sat squarely in Productivity FUE territory. We submitted three months of measured transaction logs for a sample population, and SAP's measurement team accepted the reclassification on evidence.
5. Negotiated a contractual price hold across the conversion window. The conversion is a multi-quarter exercise. We negotiated a contractual hold on FUE unit pricing through go-live plus 18 months, removing the risk that SAP would retrade unit pricing once the conversion was committed. The clause also included a defined process for FUE true-up post-go-live based on measured consumption rather than projected sizing.
6. Documented the FUE methodology for the next cycle. The methodology and the supporting transaction analysis became a documented internal asset. The utility's procurement team now runs the same analysis quarterly, so the next renewal or cycle begins from a defended position rather than a SAP-supplied number.

The Outcome

The signed conversion Order Form delivered a contracted FUE count 40 to 45 percent below SAP's initial sizing proposal. The Compatibility Pack risk overlay was removed at no additional cost. The annual licence cost trajectory through the conversion window held flat in real terms versus the pre-conversion baseline, which preserved the conversion business case the board had approved. The contractual price hold and the defined post-go-live true-up methodology removed the principal pricing risks the CIO had flagged before engagement.

Three structural protections sit in the new Order Form. First, the FUE conversion ratios are explicitly defined for this customer, preventing SAP from quietly reapplying a different methodology in a future cycle. Second, the Compatibility Pack scope is contractually extended for a defined window, with a documented decommissioning plan. Third, the post-go-live true-up provisions specify measurement evidence and a dispute-resolution process, so any future FUE adjustment runs through an evidentiary process rather than a SAP-controlled measurement.

What Other Enterprises Can Take From This

S/4HANA conversion sizing is the moment SAP's commercial team adjusts your future cost base. The exercise is presented as technical, but the FUE allocation drives the licensing economics for the next 5 to 10 years. SAP's defaults sit at the upper edge of what the price list permits. The Functional and Productivity FUE categories carry lower unit costs than Professional FUE, and the eligibility for those categories is determined by transaction profile, not by job title. Most internal SAP teams accept the SAP-supplied allocation without independent transaction analysis. The cost of that acceptance compounds over years.

Compatibility Pack handling is the second under-appreciated risk. SAP's official position is that legacy ECC functionality will transition through Compatibility Packs for a defined period, with eventual deprecation. The transition window is a commercial opportunity for SAP unless the buyer contracts explicitly for the scope and duration. Without a written agreement, the buyer pays twice: once in FUE to access the legacy functions during transition, and again to migrate to the S/4HANA-native replacement when SAP withdraws the pack.

For asset-heavy and regulated utilities, the conversion timing also interacts with the 2027 deadline. SAP knows that ECC mainstream maintenance ends in 2027, and the commercial pressure to convert builds quarter by quarter. The right defence is timing optionality: maintain an evidenced plan for extended maintenance or third-party support as a credible alternative, even if the eventual choice is conversion. The optionality reshapes the SAP commercial conversation. Our S/4HANA licensing guide walks through the FUE math, the Compatibility Pack mechanics, and the contract conversion paths that drive these outcomes.