The inventory KPIs that actually predict ecommerce profitability

Sell-through measures the percentage of a given inventory buy that has been sold within a defined window. For seasonal ecommerce brands, the useful window is usually the length of the season — 12 to 20 weeks — rather than a calendar month. Sell-through calculated on the wrong window either flatters the number (too long) or panics the team (too short).

Reversify tracks sell-through per SKU against its own launch curve, so you know at week four whether a style is tracking ahead, on pace, or behind. That framing turns sell-through into a leading indicator instead of a lagging report.

Days on hand is the average number of days a unit sits in your warehouse before it sells. Stock turn is the annualized version of the same idea. Both are useful because they translate directly into working-capital tied up, but both are averages, which means they hide the shape of the distribution.

The better view — and the one Reversify defaults to — is a percentile breakdown. Your median SKU might turn every 45 days, but the 90th percentile might sit for 180. That long tail is where cash gets stuck, and it is the number that predicts the size of your end-of-season markdown bill.

Gross margin return on inventory investment is calculated as gross margin dollars divided by average inventory cost over the same period. It condenses both margin and turn into a single ratio: how many gross margin dollars are you earning per dollar of inventory investment? A GMROI of 3 means you earned three dollars of gross margin for every dollar tied up in inventory over the year.

GMROI is the metric to review with finance, because it maps cleanly to cash efficiency. A high-margin SKU with low turn can have a worse GMROI than a lower-margin SKU that moves quickly. Reversify surfaces the ranking so you can see where the actual efficiency lives in the catalog.

The dead-stock ratio is the share of on-hand inventory value that has no realistic path to full-price sale. The at-risk ratio is the broader share that is trending toward dead stock at current velocity. Together they give you an early-warning system for markdown pressure.

Most brands underestimate both numbers. Reversify calculates them continuously based on your own velocity and margin history, and flags the categories where the at-risk ratio is climbing. Acting on that signal in weeks rather than months is worth several margin points per year.

The KPI that most inventory dashboards forget entirely: the margin on units after returns settle. A SKU with a 50% gross margin and a 30% return rate can have a real margin closer to 25% once return shipping, restocking, and markdown of returned units is included. Any inventory KPI that ignores that math will over-value the wrong SKUs.

Reversify computes return-adjusted margin natively and uses it as the primary margin input into GMROI and health scoring. That single change often re-orders the top and bottom of the catalog.