Rack Type Capacity Comparator
Compare two rack types on cost per unit actually stored, not raw density, once each is checked against a required capacity.
Sensitivity to required capacity
| Scenario | Required capacity | Verdict |
|---|---|---|
| -20% | 12,000 | Rack A |
| -10% | 13,500 | Rack A |
| Entered (15000 units) | 15,000 | Rack A |
| +10% | 16,500 | Rack A |
| +20% | 18,000 | Rack A |
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Based on your results, these related decisions are available.
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How this works
A denser rack type looks like the obvious pick once footprint is fixed, but density and installed cost don't scale together. Total capacity and total installed cost both scale with the same footprint, so comparing rack types actually means comparing cost per unit stored, not raw density. This engine only considers an option viable if its resulting capacity meets the required capacity, then picks the lower cost per unit stored among the options that qualify.
Key terms
- Density: units held per storage location, for each rack type.
- Cost per unit stored: total installed cost for the footprint divided by that rack type's total capacity, the figure the verdict actually turns on.
- Fits: whether a rack type's resulting capacity meets or exceeds the required capacity at all.
Assumptions
- Uniform installed cost per location for each rack type
- Footprint is fully racked with one type at a time, not a mixed layout
Limitations
- Two options only, not an open-ended rack catalog
- Does not model labor or pick-time differences between rack types, denser rack types are often slower to pick, a real tradeoff not captured here
Sources
Frazelle's World-Class Warehousing and Material Handling rack-selection cost-per-storage-unit treatment.
Worked example
With a 15,000-unit requirement and a 500-location footprint, Rack B stores 75% more units per location than Rack A (70 vs 40) and comfortably clears the requirement at 35,000 units of capacity. But Rack B's installed cost is high enough that it costs $3.57/unit stored, while Rack A costs only $2.25/unit stored at 20,000 units of capacity, still well above the requirement. Rack A is both less dense and cheaper per unit stored, so it wins even though Rack B looks like the "better" option by density alone.
Common use cases
- Choosing between two rack systems for a new or expanded storage footprint
- Checking whether a denser, more expensive rack type actually earns its premium
- Screening rack options against a required capacity before committing to installed cost
- Continuing from Warehouse Capacity Planner's total capacity figure into a rack-level decision