Does Tailored Fit Pricing always save money versus sub-capacity?

No. Tailored Fit Pricing (TFP) and the R4HA sub-capacity model save in different situations, so neither always wins. Sub-capacity bills on the Rolling 4-Hour Average peak, which rewards an estate that has already invested in soft capping and peak shaping to suppress that peak. TFP removes the R4HA peak and prices on full measured consumption with discounted growth and operational freedom, which favors an estate that has growth ahead, runs near its cap, or is constrained operationally by capping. An estate that has already squeezed its R4HA hard can find that TFP, by pricing the consumption it had been hiding under the peak, costs more, not less. The answer depends on the workload profile, so model both before switching.

What is the main difference between TFP and sub-capacity?

Sub-capacity prices on the Rolling 4-Hour Average, the highest 4-hour average MSU utilization measured each month, so the monthly peak drives the bill and managing that peak with capping lowers cost. Tailored Fit Pricing replaces the R4HA mechanic: it prices on total measured consumption over a baseline with a discounted rate for growth above it, and it removes the technical incentive to soft cap, so workloads can run without the peak management that R4HA demands. In short, sub-capacity is a peak based model that rewards capping discipline, while TFP is a consumption based model that rewards growth and operational freedom.

Who benefits most from moving to Tailored Fit Pricing?

Estates with growth ahead benefit most, because TFP discounts measured MSU growth above the baseline rather than charging the full sub-capacity rate on a rising peak. Estates that are operationally constrained by soft capping, for example shops whose batch windows are squeezed by the need to suppress the R4HA, also benefit because TFP removes the technical capping incentive. Conversely, an estate that runs flat and has already optimized its R4HA aggressively has the least to gain and the most to lose, because TFP would price the full consumption that peak management had been keeping off the bill. The deciding factors are your growth trajectory and how hard you already cap.

Tailored Fit Pricing vs Sub-Capacity

Tailored Fit Pricing vs sub-capacity: which actually saves more.

Neither model wins universally. Sub-capacity rewards an estate that already shapes its R4HA peak. Tailored Fit Pricing removes the peak and prices full consumption with growth discounts and operational freedom. The right answer is the one your workload profile and growth trajectory point to, and you only know it by modeling both.

Move to Tailored Fit Pricing (TFP) if you have measured MSU growth ahead or your operations are constrained by soft capping. Stay on sub-capacity if your estate runs flat and you have already optimized the Rolling 4-Hour Average hard. The trap is assuming TFP is automatically cheaper because it is newer and cloud like. For an estate that has spent years suppressing its R4HA peak, TFP can price the consumption that peak management was keeping off the bill, and cost more. The decision is an arithmetic one, not a fashion one.

TFP vs sub-capacity, the levers compared
Dimension	Sub-capacity (R4HA)	Tailored Fit Pricing
Pricing basis	Rolling 4-Hour Average monthly peak	Total measured consumption over a baseline
What lowers the bill	Shaping and capping the peak	Negotiating the baseline and growth rate
Growth treatment	Full rate on a rising peak	Discounted rate on measured growth
Soft capping incentive	Strong, capping suppresses cost	Removed, run without capping constraint
Predictability	Varies with monthly peak	More predictable, baseline plus growth
Best for	Flat estates already optimized on R4HA	Growing or capping constrained estates
Main watch out	Peak management overhead and risk	Baseline set too high; consumption now fully priced

TFP vs sub-capacity, the levers compared

Dimension

Sub-capacity (R4HA)

Tailored Fit Pricing

Pricing basis

Rolling 4-Hour Average monthly peak

Total measured consumption over a baseline

What lowers the bill

Shaping and capping the peak

Negotiating the baseline and growth rate

Growth treatment

Full rate on a rising peak

Discounted rate on measured growth

Soft capping incentive

Strong, capping suppresses cost

Removed, run without capping constraint

Predictability

Varies with monthly peak

More predictable, baseline plus growth

Best for

Flat estates already optimized on R4HA

Growing or capping constrained estates

Main watch out

Peak management overhead and risk

Baseline set too high; consumption now fully priced

Map your estate to the model whose incentive matches how you actually run:

Lean Tailored Fit Pricing if

You have real, measured MSU growth ahead and want it priced at a discount rather than at the full peak rate
Soft capping is constraining your batch windows or forcing operational compromises you would rather drop
You value predictable, baseline plus growth budgeting over chasing a monthly peak

Stay on sub-capacity if

Your estate is flat or shrinking and you have already invested in disciplined R4HA peak management
Your peaks are genuinely controllable and capping costs you little operationally
A TFP baseline offer would lock in consumption you are currently keeping off the bill

The single most important move either way is to validate the baseline. A TFP deal is only as good as the consumption baseline it is built on, and that figure, like an R4HA measurement, must be measured and challenged independently before you sign.

Does TFP always save money?No. It wins for growth and capping constrained estates and can lose for flat estates that already optimized the R4HA, because it prices the consumption peak management was hiding. Model both.

What is the core difference?Sub-capacity prices the R4HA monthly peak and rewards capping. TFP prices total consumption over a baseline with discounted growth and removes the capping incentive.

Who gains most from TFP?Estates with measured growth ahead or operations constrained by soft capping. Flat, already optimized estates gain least and risk most.

What is the key safeguard?Validate the baseline independently. A TFP deal is only as good as the consumption baseline it is built on, exactly as an R4HA figure must be challenged.

The newer model is not automatically the cheaper one.

Explainers: the Rolling 4-Hour Average explained, hardware model capacity ratings and software cost, and zIIP engines and software cost offload. Other comparisons: annual vs multi year terms and in house vs outsourced mainframe. Hub and commercial: the IBM buyer side guide, mainframe cost optimization, and mainframe contract review.

Tailored Fit Pricing vs sub-capacity: which actually saves more.

The verdict

Head to head

Who should pick which

Frequently asked

We model both before you switch. The arithmetic decides.