Assortment Planning
Assortment planning is the merchandising process by which apparel brands determine the breadth and depth of products to carry in a given season, channel, or location — defining which styles, colors, and sizes to offer and at what quantities.
What is assortment planning?
Assortment planning is the merchandising process by which apparel brands determine the breadth and depth of products they will offer in a given season, channel, or location. It defines which styles, colors, and sizes to carry, at what quantities, and across which selling channels.
Assortment planning operates within the financial constraints established by OTB planning and produces the product-level decisions that feed into buy planning and eventually purchase order generation.
In practical terms, a completed assortment plan answers:
- Which products — style, category, silhouette, colorway, fabrication
- How many units — depth per style-color-size combination
- For which channels — DTC, wholesale accounts, stores (and at what splits)
- In what season — Spring/Summer or Fall/Winter, with delivery window targets
Breadth vs depth in assortment planning
Every assortment plan involves a tradeoff between breadth (the number of distinct SKUs) and depth (units per SKU). This tradeoff has direct margin implications:
Broad assortments increase customer choice and reduce individual stockout risk but require more capital, create greater markdown exposure across a larger SKU count, and add operational complexity in planning, buying, and allocation.
Deep assortments concentrate purchasing behind fewer styles, reducing markdown risk on any individual SKU and simplifying the buy plan — but increasing the consequence if a single style underperforms.
Most apparel brands target a deliberate balance, informed by prior-season sell-through data. Styles that sold through at high rates warrant deeper buys. Trend tests and new introductions warrant shallow commitments until performance is established.
The role of OTB in assortment planning
Assortment planning cannot happen in isolation from OTB. The OTB position sets the financial ceiling for the entire assortment, by department and by channel. Assortment decisions that exceed OTB at any level — whether total, department, or channel — require either cutting product or revising the financial plan.
In practice, assortment planning and OTB management run as iterative loops rather than sequential steps. An initial assortment draft is tested against OTB; styles are added, cut, or depth-adjusted until the plan lands within budget at every level of the hierarchy.
Apparel-specific complexity in assortment planning
Apparel assortment planning has complexities that general retail planning frameworks do not fully address:
Size curves: Every style must be planned at the size level. The size distribution (small/medium/large/XL ratios) affects total unit count, cost, and ultimately sell-through. Size curves must be applied style-by-style, informed by historical residual data.
Seasonal structure: Apparel assortments are organized by season, with distinct Spring/Summer and Fall/Winter frameworks. Carry-over styles (products that continue from one season to the next) require different planning logic than new introductions.
Collection hierarchy: Styles belong to collections, which have shared themes, delivery windows, and price tier targets. Assortment decisions made at the collection level cascade to the style and SKU level.
Multi-channel variation: A DTC assortment may include exclusive colorways, limited-edition products, and premium price tiers not available in wholesale. Wholesale line sheets are built to account holder requirements and floor set schedules. The same style may exist in the assortment at different depths across channels.
In RetailNorthstar: Assortment planning is directly connected to the OTB position — style additions and depth changes update the OTB in real time. Size curves are stored and applied automatically across the buy. Collection structure is a native hierarchy in the data model, not a spreadsheet workaround.