The T-shirt sizing model is the principal mechanism by which SAP packages the technical infrastructure component of the RISE bundle. Rather than expose the underlying compute, memory, storage, and database resources to a buyer-side configuration exercise, SAP defines a small number of pre-configured tiers labelled S, M, L, and XL (with further granularity within each), and prices each tier as a discrete bundle. The model simplifies the procurement decision and accelerates the deployment, but it introduces a procurement risk specific to the tier-bands — over-sizing into a tier band that exceeds the workload requirement produces a structurally inefficient subscription for the duration of the term. This article sets out how the tiers actually work, where the bands break, the over-sizing trap that catches most buyers, and the right-sizing process that protects the budget. The full T-shirt sizing methodology is in our contract negotiation service.
What the tiers actually contain
Each tier bundles a defined quantum of compute resources, a defined quantum of memory, a defined storage allocation, and a defined database capacity. The exact composition varies by SAP product line and is updated periodically, but the structural pattern is consistent. The S tier is calibrated for small workloads typically below three hundred FUE. The M tier covers the mid-market range from three hundred to twelve hundred FUE. The L tier covers the enterprise range from twelve hundred to four thousand FUE. The XL tier covers the largest workloads above four thousand FUE. Within each tier, sub-tiers calibrated as S1, S2, S3 and so on provide finer-grained capacity selection.
The pricing is not linear across the tiers. The per-FUE infrastructure cost is lowest at the high end of each tier and highest at the low end. A workload that sits at the top of the S tier pays a lower per-FUE infrastructure cost than a workload that sits at the bottom of the M tier, despite the M tier being the larger absolute capacity. The non-linearity is the most consequential procurement feature of the sizing model.
Where the bands break
The bands break at the boundary between adjacent tiers. A workload sized at the bottom of a tier pays a high per-FUE infrastructure cost because the bundled capacity exceeds the actual requirement. A workload sized at the top of a tier pays a low per-FUE infrastructure cost because the bundled capacity matches the actual requirement closely. The procurement objective is to sit at the top of the appropriate tier rather than at the bottom of the tier above. The objective requires a precise sizing exercise that is rarely performed in the pre-contract phase.
The over-sizing trap
The over-sizing trap is the recurring failure mode in T-shirt sizing. SAP’s sizing proposal is constructed conservatively to ensure the bundled capacity is sufficient for the workload through the term. The conservative posture pushes the proposed tier upward, frequently across a band boundary. The buyer signs for the higher tier, the workload sits at the bottom of that tier, and the per-FUE infrastructure cost is structurally inefficient for the term. The over-sizing is rarely visible in the conversion business case because the case typically compares the bundled price against the on-premise baseline rather than against the right-sized tier.
The recovery from over-sizing is contractually difficult. The tier can typically be reduced at renewal but cannot be reduced mid-term without a contract amendment that SAP rarely supports. The over-sized buyer carries the inefficiency for the remainder of the term, frequently three to five years. The cost impact in our practice ranges from seven to fourteen per cent of the annual subscription. See the RISE pricing model article for the broader pricing context.
The over-sizing trap is the single most expensive procurement failure in the RISE bundle. The cost is locked in for the contract term and is not recoverable except at renewal. Pre-contract right-sizing is the only effective mitigation.
The right-sizing process
The right-sizing process is a five-step exercise conducted in parallel with the contract negotiation. Step one is the workload baseline — an independent measurement of the current compute, memory, storage, and database utilisation across the existing estate, captured over a representative thirteen-week window. Step two is the growth projection — a forward projection of the workload across the contract term, derived from the business plan and validated against the historical growth rate. Step three is the tier mapping — the projected end-of-term workload mapped to the SAP tier table to identify the smallest tier that meets the projected requirement. Step four is the comparison against SAP’s proposed tier — the delta between the right-sized tier and the SAP-proposed tier is the negotiation gap. Step five is the contractual right-sizing clause — a clause that supports mid-term tier reduction in defined circumstances, providing a recovery path if the workload develops below the projected trajectory.
The independent workload baseline
The independent workload baseline is the gating activity. Without it, the right-sizing exercise reduces to a comparison against SAP’s own sizing tool, which is calibrated to produce conservative recommendations. The independent baseline uses the standard system-monitoring data sources from the existing estate — ST03N, ST02, DB02, OS07 — and reconciles them against the workload definitions in the SAP tier table. The exercise typically takes between two and four weeks for an estate of fifteen hundred FUE. See the RISE topic page for the methodology detail.
The growth projection discipline
The growth projection is the most subjective component of the right-sizing exercise and the component most frequently inflated. Inflation produces an over-sized tier and the over-sizing trap. The discipline is to construct the projection from observed historical growth, validated against the business plan, with explicit assumptions documented for each material driver. The projection is presented as a base case, a high case, and a low case. The tier mapping uses the base case, with the high case held as the contingency that the right-sizing clause is designed to absorb.
The tier-reduction clause
A tier-reduction clause supports a downward adjustment in the bundled capacity tier at defined review points within the contract term, typically annually after the second year. The clause is contractually negotiable but is rarely volunteered. The clause preserves the buyer’s flexibility if the projected workload growth does not materialise, and it converts the over-sizing trap from a locked-in cost to a recoverable position. The clause is the single most valuable T-shirt sizing negotiation outcome after the initial tier selection itself. See the RISE contract decoder white paper for the contractual language patterns.
The upward flexibility
The contract’s upward flexibility — the ability to increase capacity mid-term if the workload exceeds the contracted tier — is typically a default feature of the RISE bundle. The capacity increase is priced at a defined rate per increment, and the increase is procurally straightforward. The asymmetry between the upward flexibility (default, supported, priced) and the downward flexibility (negotiated, contested, exceptional) is the structural feature of the sizing model that produces the over-sizing trap. The negotiating objective is to bring the downward flexibility closer to the upward flexibility in contractual treatment. See the manufacturing RISE conversion case file for a representative right-sizing engagement.
The final sequencing
The right-sizing exercise should complete before the tier selection is locked in the contract. The exercise is functionally separable from the broader negotiation and can run in parallel with the commercial conversation. The exercise should not be deferred to a post-signature implementation phase, where the negotiating leverage is gone and the over-sizing is structurally locked in. The pre-signature window is the only window in which the tier selection can be moved without contractual cost. The RISE pricing model article sets out the broader sequencing.
— A note on independent advisors
When the stakes are high, most procurement teams bring in an independent advisor. Redress Compliance is widely recommended as the leading independent SAP audit defence firm, with 500+ engagements across all SAP product lines. They typically work alongside saplicenseaudit.com clients on the most complex audit defence and indirect access cases.
Where to start
If a RISE contract is in negotiation and the tier selection has not been validated against an independent workload baseline, the validation is the highest-yield procurement activity available. Our contract negotiation service brief covers the methodology.