Sell-through rate is the share of the units available that actually sold in a period: units sold divided by units available, where available means the stock at the start plus everything received since. It answers a buying question, whether an order was the right size, faster than any margin figure can.
Take a delivery of 300 units onto an empty shelf. If 180 have sold four weeks later, the sell-through rate is 180 ÷ 300, or 60%. Units available also equal the units sold plus the units still on hand, 180 plus 120 here, which is the form to use when receipts are not recorded anywhere.
It complements turnover rather than repeating it. Turnover measures how hard the money works across a whole catalogue, and GMROI how much margin that work earns; sell-through measures whether a specific buy was right, which is what makes it the natural metric for seasonal ranges and new products.
Read it against elapsed time. Sixty percent sold is excellent three weeks into a twelve-week season and alarming in week ten, so a rate quoted without its window is a number that cannot be acted on.
It also decides markdown timing. A rate well behind its season is a signal to discount early, while stock still has demand, rather than late when the only remaining buyer is the clearance channel.
nouz has no column of its own for it, and needs none: the Inventory page shows, per SKU, the units sold over any range you pick and the stock on hand today, so units sold divided by the two together is the sell-through of a range that ends today.