Inventory turnover and weeks of supply in fashion

Zara can move a new design from sketch to store shelf in roughly two to three weeks, then sell through it and replace it before a competitor has finished its sample review. A luxury house like Hermès does almost the opposite: it deliberately makes fewer bags than buyers want, and a Birkin can sit in a controlled allocation system for a long time. These two companies live at opposite ends of a single financial ratio. Learn to read it, and you can diagnose a fashion business model from one number.

What inventory turnover actually measures

Inventory turnover (also called "inventory turns" or "stock turn") tells you how many times a company sells and replaces its entire inventory in a year. Higher means faster selling.

The standard formula:

Inventory Turnover = Cost of Goods Sold (COGS) / Average Inventory

• COGS: what it cost the company to make or buy the goods it sold (not the retail price). Found on the income statement.
• Average Inventory: usually (beginning inventory + ending inventory) / 2, taken from the balance sheet.

You use COGS, not revenue, because inventory is carried on the books at cost. Mixing cost and retail price inflates the ratio and makes comparisons meaningless.

Weeks of supply: the same idea, flipped

Merchandisers often prefer weeks of supply (WOS), which answers a more intuitive question: at the current selling pace, how many weeks would my current stock last?

Weeks of Supply = (Average Inventory / COGS) x 52

Or simply: 52 / Inventory Turnover.

A turn of 4x equals 13 weeks of supply. A turn of 12x equals about 4.3 weeks. Same fact, two languages. Finance teams talk in turns; buying and planning teams talk in weeks.

A worked example

Imagine a mid-market apparel brand, "NordAtlantic Denim":

• COGS for the year: 200 million euros
• Inventory at start of year: 45 million euros
• Inventory at end of year: 55 million euros

Average inventory = (45 + 55) / 2 = 50 million euros

Inventory turnover = 200 / 50 = 4.0x

Weeks of supply = 52 / 4.0 = 13 weeks

So NordAtlantic sells through its stock four times a year, and at any moment holds about a quarter's worth of goods. That is a typical, unremarkable figure for a full-price wholesale-and-retail apparel brand.

Now cut the average inventory to 25 million euros with the same COGS. Turns jump to 8x, WOS drops to 6.5 weeks. Half the capital tied up, twice the velocity. That is the prize, and the risk, of fast inventory.

Why 4x and 12x are two different businesses

Turnover is not a "higher is always better" score. It reveals a strategy.

Fast fashion: velocity is the model

Zara (owned by Inditex, the world's largest fashion retailer by revenue) runs deliberately short production runs and restocks winners quickly. Inditex has historically reported inventory turnover in the range of roughly 3.5x to 4x on a full-year basis (per its published annual reports; treat exact figures as year-dependent estimates). That may sound modest, but the reported ratio hides the real story: individual items turn extremely fast because Zara refreshes assortments constantly and keeps little safety stock of any single style.

The financial payoff of fast turns:

• Less capital frozen in unsold goods
• Fewer markdowns (a markdown is a price cut to clear slow stock, which destroys gross margingross marginGross margin is the share of revenue left after subtracting the direct cost of producing goods or services, expressed as a percentage of revenue.View full definition →)
• Lower risk of obsolescence, critical when trends die in weeks

The danger: stockouts and the operational cost of a hyper-responsive supply chain.

Luxury: scarcity is the model

A luxury house does not want to turn fast. Hermès (part of the broader luxury landscape alongside groups like LVMH and Kering) protects brand desirability by keeping supply below demand. Luxury inventory also includes slow-moving, high-value raw materials (leather, precious metals) and finished goods that hold value over time rather than expiring like a seasonal trend.

Luxury turns are structurally lower, often in the low single digits, and that is by design, not by failure. A watch or a handbag does not "go out of fashion" the way a printed summer dress does. Holding it is not the same risk.

The trap for a beginner analyst: seeing a luxury turn of 2x to 3x and calling it "inefficient." It is not. Compare like with like.

Reading the number in context

Benchmarks by segment (directional estimates)

These are broad, directional ranges commonly seen in retail analysis, not precise figures. Always pull the actual number from a company's annual report.

The US and Europe track closely here because the underlying business models are global. The bigger regional difference sits in the calendar: US markdown cycles cluster around Black Friday and end-of-season clearance, while many European retailers operate within regulated sale periods (for example, France's official winter and summer "soldes"). Those rules shape when inventory gets flushed and can distort a single quarter's WOS.

For definitions and how these ratios sit alongside other efficiency metrics, Investopedia's inventory turnover explainer is a solid free reference.

Seasonality wrecks simple averages

Fashion is brutally seasonal. Measuring inventory only at year-end can mislead badly, because year-end may fall right after a big clearance when stock is artificially low. Serious analysts use a monthly or 13-point average (each month-end plus the opening balance) to smooth this out. If you only have two data points, know that your ratio is a rough cut.

The metric that connects to cash

Turnover is not just an operational stat. It feeds directly into cash. Days Inventory Outstanding (DIO) converts turns into days:

DIO = 365 / Inventory Turnover

NordAtlantic's 4.0x turn = about 91 days of inventory. That 91 days is money sitting on shelves and in warehouses, not in the bank. DIO is one of three components of the cash conversion cycle, the number of days between paying suppliers and collecting cash from customers. Faster inventory turns shrink that cycle and free up working capitalworking capitalWorking capital is the difference between a company's current assets and current liabilities, measuring short-term liquidity and the funds available to run daily operations.View full definition →, which is exactly why Zara's model is so cash-efficient despite thin markdowns.

For a fashion CFO, a one-week improvement in weeks of supply across a large business can release tens of millions in cash. That is why planning teams obsess over it.

Common mistakes when using the ratio

• Using revenue instead of COGS. This inflates turns and breaks any comparison with a company that did it correctly.
• Comparing across segments. A 3x luxury turn versus a 5x fast-fashion turn is not a ranking. It is two strategies.
• Ignoring channel mix. A brand with heavy e-commerce may hold centralized stock differently from a store-heavy peer, changing the ratio's meaning.
• Trusting one snapshot. Seasonality demands averaging. A single balance sheet date can flatter or punish a healthy business.
• Forgetting quality of inventory. High turns achieved by dumping stock at deep markdowns is bad turnover. Always read turns alongside gross margin and markdown rates.

Putting it together

When you see a fashion company's turns, ask three questions in order. What segment is it (which sets the expected range)? Is the number trending up or down over several years (direction matters more than the absolute level)? And how did it get there, healthy full-price sell-through or panic markdowns? Answer those and you understand the business, not just the arithmetic.

Key Takeaways

• Inventory turnover = COGS / Average Inventory. Weeks of supply = 52 / turnover. They are the same fact in two languages.
• Always use COGS, not revenue, and always average inventory across the year to handle fashion's heavy seasonality.
• Turnover reveals a business model, not a quality score. Fast fashion pursues high velocity to cut markdowns and free cash; luxury keeps turns low on purpose to protect scarcity and desirability.
• Directional benchmarks (estimates): value and fast fashion roughly 4x to 6x, mainstream apparel 3x to 4x, luxury often 1x to 3x. Confirm with the company's actual annual report.
• Turns drive cash. They convert to Days Inventory Outstanding and feed the cash conversion cycle, so shaving weeks of supply can release large amounts of working capital.