Find your sell-through rate — the share of received stock that sold in a period — plus what's left and how long it lasts at the current pace.
Sell-through rate = units sold ÷ units received, over a period (often a month). High rates suggest reordering; low rates suggest overbuying or the need for a markdown. Weeks-of-stock assumes the current sales pace continues. General information only.
Sell-through rate is the percentage of stock that sold versus what you brought in over a period. It's the retailer's pulse-check: a high rate means demand is outrunning supply (reorder), a low rate means cash is stuck on the shelf (markdown or buy less next time). Pair it with weeks-of-stock to time your reorders.
Sell-through rate = units sold ÷ units received
Sell-through rate is the share of the stock you brought in during a period that went back out again in the same period. It is a buying scorecard more than a sales one: it grades the decision you made when you placed the order against what customers actually did. A high rate says you judged demand well or under-bought; a low rate says cash is sitting on a shelf. Because it compares sold against received rather than against total stock on hand, it reads the freshness of a specific buy rather than the health of the whole inventory.
What it ignores is margin. Nothing in the ratio knows what you paid or charged, so a 90% rate achieved by discounting to clear looks identical to 90% at full price and means something completely different. It also ignores substitution — units bought because the customer's first choice was out of stock still count here.
The calculator opens with 140 units sold against 200 units received over a four-week period. The rate is 140 ÷ 200 = 70%. Units remaining are 200 − 140 = 60. The selling pace is 140 ÷ 4 = 35 units a week, so weeks of stock left is 60 ÷ 35 = 1.7 weeks. The tool reads 70% as Healthy — strong enough that the buy was sound, short of the 80% line where it starts warning that you may have under-ordered and left sales unmade.
The two numbers point in slightly different directions, and that is the useful part. 70% over four weeks is a comfortable result. 1.7 weeks of cover is not comfortable at all if your supplier needs three weeks to deliver: on those defaults the reorder should already have been placed, roughly a week and a half ago. Sell-through grades the past buy; weeks-of-stock is the one that tells you what to do this morning.
The 1.7 weeks depends entirely on 35 units a week continuing. That assumption is fine for a staple and poor for anything seasonal, promotional or newly launched. New products usually front-load — a large share of the four weeks' sales happen in week one — so the average pace overstates what is left to come, and the real weeks-of-stock is longer than the tool says. Items heading into their season do the opposite and the true figure is shorter. If the weekly split is lopsided, recompute the pace on the last week or two rather than the period average before you act on it.
The first is comparing rates across different period lengths — a 70% four-week figure and a 70% weekly figure describe very different businesses, and the period is the part everyone drops when quoting the number. The second is measuring sell-through on discounted units without recording the discount, which turns a margin problem into an apparent success. The third is reading a blended rate across a whole category: if one SKU clears at 95% and another at 20%, the 70% average describes neither, and the reorder decision is per SKU. The fourth is ignoring returns — units sold and later returned inflate the rate and the restocked units quietly reappear as inventory. The fifth is reordering on rate alone while ignoring weeks-of-stock and lead time, which is how a strong seller goes out of stock in a good month.
One rate describes one product for one period. Buying decisions need the grid: every SKU, several periods, with cost, selling price and realised margin beside the rate so that a high sell-through achieved on markdown is visible as what it is. Add lead time per supplier and the reorder point stops being a judgement call and becomes arithmetic. That is spreadsheet territory rather than calculator territory — our Etsy Seller COGS & Profit Tracker keeps the units, costs and margins together so the rate can be read next to the money it made.
Often benchmarked around 40–80% per month depending on category. Very high can mean you're leaving sales on the table by under-stocking; very low ties up cash.
Monthly is the common window, but fast-moving goods use weekly. Match the period to how quickly you reorder.
Related: inventory turnover calculator · ecommerce profit calculator · average order value calculator · all free calculators.
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Last reviewed: September 2026. Free to use, no signup — Sell-Through Rate Calculator by ToolWise Digital.
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