Style-Color Depth Formula
How apparel teams calculate units per style-color combination — the depth number that determines whether a SKU will land at full price or in the markdown bin.
What Style-Color Depth measures
Style-color depth is the average number of units behind every style-color combination in a buy. It is the single best proxy for whether an assortment will drive sell-through or spread itself thin.
Units per Style-Color = Total Buy Units ÷ (Styles × Colors)Thin depth starves size coverage, hurts vendor MOQ economics, and undercuts marketing efficiency. Deep per-style-color supports strong sell-through but concentrates risk in fewer bets.
Worked apparel example
A brand is buying 6,000 units across 25 styles and 3 colors per style.
Depth per Style-Color = 6,000 ÷ (25 × 3) = 80 units
80 units per style-color is lean but workable if the size curve is controlled (5–6 core sizes). The same 6,000 units spread across 40 styles and 4 colors drops to 37 units per style-color — below the threshold where size coverage works.
80 units per style-color supports a standard size run.
Failure modes we see
Breadth traps. A brand that feels it "needs more newness" adds SKUs without increasing total units. Depth per style-color drops. Sizes are missed. Sell-through falls. Markdown rises. Next season, the brand concludes the problem was "not enough newness" and adds more SKUs.
- MOQ-driven thin-depth. Vendor MOQs force a minimum buy per style-color; brand adds marginal styles just to hit other MOQs, spreading units thin.
- No depth target per category. Core basics can run 200+ units per style-color; fashion can run 40. Without a category-specific target, brands spread depth uniformly.
How RetailNorthstar handles depth
The line plan shows depth per style-color against category targets. As styles are added, the system flags depth falling below the threshold for the category — breadth traps prevented at concept, not discovered at hindsight.
Related formulas
- Total Line Count — the denominator
- Size Curve Allocation — how depth distributes across sizes
- Sell-Through Rate — the downstream signal
See depth-by-category flagged live in RetailNorthstar — before the line plan is committed.
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