Footwear size curves: why one style is actually 12+ SKUs (and what that does to your cash flow)

If you're launching or scaling a footwear brand, you've probably already felt this — one style doesn't mean one product. It means 12, sometimes 14, sometimes more.

That's the reality of footwear size curves, and it has real consequences for your cash flow, your inventory strategy, and your ops.

What a footwear size curve actually is

A size curve is the distribution of units you order across a size run. If you're carrying women's sizes 6-11 in a single style, that's already 6 sizes. Add half sizes and you're at 11. Add wide widths and you're at 22.

Each one of those is a distinct SKU — its own barcode, its own inventory position, its own carrying cost.

Most brands understand this intellectually. Fewer understand what it actually means for the way they buy inventory.

Why one style equals 12+ SKUs

Here's a simple example. You launch a women's sneaker in one colorway:

• Sizes 6-11 in full sizes = 6 SKUs
• Add half sizes (6.5-10.5) = 10 additional SKUs
• Add one wide width option = 16 SKUs
• Add a second colorway = 32 SKUs

That's 32 inventory positions from what started as a single product idea.

For brands buying 500 units of a style, that's an average of fewer than 16 units per SKU before you even account for the fact that your size curve isn't flat. Sizes 7.5-9.5 will sell. Size 11 wide may not.

The Footwear Distributors and Retailers of America (FDRA) notes that inventory planning is one of the top operational challenges in the industry — precisely because of this fragmentation at the SKU level.

What this does to your cash flow

SKU proliferation is a cash flow problem as much as it's an ops problem.

When you're buying across a full size run, you're committing capital to sizes that will move at very different rates. The middle of your curve will sell through. The tails — your 5s, your 12s, your wide widths — will sit.

That sitting inventory costs you in three ways:

1. Carrying costs add up. Warehouse space, 3PL pick-and-pack fees, and insurance don't care whether a size 5 ever ships. You're paying for it.

2. You tie up open-to-buy. Every slow-moving SKU is capital you can't redeploy into a top-seller reorder. For scaling brands, this is where growth stalls.

3. Markdowns hit margin. When you eventually clear out your tail sizes, you're discounting. That margin erosion compounds quickly when it happens across every style you carry.

How to build a smarter size curve

This is where brands that scale well start to pull ahead. Instead of ordering symmetrically across a full size run, they buy to their actual sell-through data.

A few things that help:

Start with a tighter initial buy. On new styles, consider a narrowed size run first — your core sizes only. Test, then expand.

Build your curve from historical data. If you have even one season of sales history, use it. Which sizes sold through at full price? Which sat? That's your curve.

Align your size curve with your channel. A style going into a boutique may have a different customer than your DTC channel. Size curves should reflect where the product is going, not just what you think will sell.

Review your curve by style type. Athletic, dress, and casual footwear often have different size distributions. A single curve doesn't fit every product.

The ops setup that makes this manageable

Getting your size curves right is partly a buying decision and partly a systems decision.

Your OMS, ERP, or inventory planning tool needs to track performance at the SKU level — not just the style level. If your reporting rolls up to the style, you can't see which sizes are pulling the curve down.

You also need clear reorder logic. When a core size hits a reorder point, you want to move fast. When a tail size sits past a threshold, you want a trigger for markdown or transfer — not a manual review six months later.

The bottom line

One style. Twelve SKUs. Real cash flow consequences.

Footwear brands that treat size curves as a planning tool — not just a buying habit — end up with less dead inventory, better margin, and more capital to grow with.

If your current process is "order the full run and see what happens," there's a better way. It starts with understanding what your curve is actually telling you.

Izba works with scaling brands to build inventory and ops systems that match the complexity of their product line. If footwear SKU management is slowing your growth, let's talk.