For your own resale inventory, pick a period and divide physical units sold during that period by physical units available for sale during that period. Multiply by 100 to get a percentage. Count a crosslisted item once. If the same coat appears on eBay and Poshmark, you own one coat, not two units of inventory.
Period sell-through = units sold ÷ (listed units at start + newly listed units during period) × 100
If you began the month with 200 listed pieces, listed 40 more, and sold 24, monthly sell-through is 24 ÷ 240 = 10%. Record returns and canceled orders consistently: an item that comes back into sellable inventory belongs in the available count again. Decide whether bundles count as physical units or lots, then keep that convention from month to month.
Your store rate and eBay's research rate answer different questions
Your store rate tells you how quickly your inventory turns into sales. eBay Product Research reports metrics, including sell-through, for matching marketplace searches. That is useful before sourcing an item: it compares demand and supply in the market. It does not measure the performance of your own bins.
The denominator also changes across common reseller shortcuts. Sold ÷ current active listings is a quick velocity ratio, but it excludes items sold or removed before the snapshot. It can exceed 100% and should not be mixed with the period formula above. The Reseller CFO tracker labels its dashboard number 90-day sell-through and uses items sold in the last 90 days ÷ (those sales + currently listed items). Use it to compare the same dashboard metric over time; use beginning inventory plus new listings when you need a period cohort calculation.
Pull the counts without counting items twice
Take active and sold counts from eBay Seller Hub and Poshmark's My Inventory Report, then reconcile them to one item list keyed by SKU. A coat sold on Poshmark must leave your eBay active list and count as one sold unit in the combined business measure. Keep the period, time zone, and counting rule beside the result. A change in any one of those can move the percentage more than a real operating improvement.
What to do with the number
Break sell-through down by category, source, or purchase month before setting a universal target. Seasonal coats and everyday replacement parts should not be judged against the same month. A lower rate can be rational if the item earns enough absolute profit and takes little space; a fast-moving category can still be weak if fees and handling eat the margin. Compare sell-through with profit per item, days held, and purchase dollars tied up.
The first useful action is simple: calculate last month for one category, then review the unsold items behind the denominator. If those items are old, use the inventory-aging review. If you cannot locate them easily, set up the SKU and bin workflow.
