Sell-through rate (STR) is the percentage of available inventory you actually sold during a period. In plain words: units sold divided by the units you had available to sell, over a set window such as 30 days. A high STR means demand is strong relative to stock, while a low STR flags slow movers tying up cash.
Why use STR instead of raw sales?
Raw sales counts favor products you stock deeply. A product that sold 50 units out of 500 in stock looks better than one that sold 30 out of 40, yet the second one is what shoppers are actually clearing out. STR normalizes demand by availability, so it surfaces products that are genuinely wanted relative to what you have on hand. We cover the mechanics and edge cases in our sell-through rate guide.
How do you use STR in merchandising?
- Ranking: weight STR in a collection sort so fast-clearing products earn top positions even when their absolute sales numbers are modest.
- Clearance: consistently low STR identifies products that need more exposure or a markdown before they become dead stock.
- Buying decisions: a high STR that holds across restocks is a clear reorder signal.
STR works best alongside other signals. Pair it with sales velocity for recency, and with inventory quantity so you do not promote something that is about to sell out.
What window should you measure over?
Match the window to how fast your catalog turns. Short windows catch trends and promotion effects quickly but jump around. Longer windows are steadier but slower to notice change. If you restock frequently, measure between restocks; if you buy seasonally, measure across the season. The wrong window does not make STR useless, it just makes it laggy or noisy, so start with 30 days and adjust.
STR is a built-in sorting signal in Dynasort. Install it from the Shopify App Store or see how it works.