What sell-through tells you
Sell-through compares units sold with the inventory that was available to sell. It is most useful when measured over a defined period such as a week, month, season, or promotion window. A high sell-through rate can mean strong demand, underbuying, or both. A low rate can mean weak demand, poor placement, oversupply, or a product that needs more time.
The metric is especially helpful for products with seasonal risk: apparel sizes, limited-run accessories, launch inventory, and items with planned receipts. It is less useful when a product was out of stock for much of the period, because sales were constrained by availability.
- Merchants use it to compare styles, sizes, and colors.
- Inventory planners use it to tune reorder quantities.
- Marketplace sellers use it to detect slow-moving stock before fees rise.
How to calculate sell-through
The standard unit formula is: sell-through rate = units sold / (beginning inventory + receipts) x 100. Beginning inventory is the on-hand count at the start of the period, and receipts are units added during the period. Ending inventory is not the denominator because it is the result of sales and receipts.
Example: a store starts the month with 80 units of a sandal, receives 40 more units, and sells 72 units. Available units were 80 + 40 = 120. Sell-through is 72 / 120 x 100 = 60 percent. If the store ended with 48 units, that ending count confirms the unit flow but does not replace the denominator.
Add weeks of supply
Sell-through is stronger when paired with weeks of supply. The simple formula is: weeks of supply = ending inventory / average weekly unit sales. If the sandal example sold 72 units over four weeks, average weekly sales were 18. Ending inventory of 48 units equals 48 / 18 = 2.7 weeks of supply.
The interpretation depends on lead time. If replenishment takes six weeks, 2.7 weeks of supply may trigger a reorder. If the item is seasonal and the season ends in three weeks, the same supply level may be appropriate.
- Use sell-through to understand demand during the period.
- Use weeks of supply to understand how long current stock may last.
- Use lead time and minimum order quantity before deciding to reorder.
Common mistakes in retail analysis
Do not mix dollars and units unless that is intentional. Unit sell-through shows physical movement; dollar sell-through can be distorted by discounts, price changes, bundles, and currency. Also avoid comparing products across periods of different length without normalizing for time.
Another mistake is ignoring stockouts. A 100 percent sell-through rate may look excellent, but if the item sold out early, true demand was higher than recorded sales. In that case, review lost sales, page views, waitlists, or store feedback before reducing future buy depth.
Frequently asked questions
What is a good sell-through rate?
It depends on category, margin, seasonality, and lead time. A fast-fashion item may need high weekly sell-through, while a core replacement part may be healthy at a slower rate.
Should receipts be included in sell-through?
Yes, if they arrived during the measured period and were available to sell. Excluding receipts makes performance look artificially high.
Is sell-through the same as inventory turnover?
No. Sell-through is usually a short-period unit metric. Inventory turnover compares cost of goods sold with average inventory over a longer accounting period.
How do markdowns affect sell-through?
Markdowns can lift unit sell-through while lowering margin. Review gross margin dollars and sell-through together before judging a promotion.