Sell-Through Rate Calculator

The maths behind it

Sell-through rate is units sold divided by units received, over a defined period: sold ÷ (beginning inventory + received) × 100. It measures how much of what you bought has actually sold.

The period is doing more work than the formula. A 60% sell-through means very different things over four weeks and over six months, and a rate quoted without its window is not a measurement.

Putting numbers to it

A buy of 280 units received at the start of a period, with 20 already on hand, 300 available. Over six weeks, 240 sell.

Sell-through is 240 ÷ 300 = 80% in six weeks, or about 13% a week. At that rate the remaining 60 units clear in another 4.5 weeks, which is comfortable.

Now the same buy selling 90 units in six weeks: 30% sell-through, 5% a week, and 210 units remaining that will take 42 weeks to clear. That product needs a markdown decision now rather than in nine months, and the sell-through rate is what surfaces it.

Where it is unreliable

A high sell-through can mean the product is popular or that you did not buy enough of it. Selling 100% of a 50-unit buy in two weeks looks excellent and may represent several hundred units of demand that went unmet.

The rate also depends on when in the season the stock arrived. A late delivery produces a poor sell-through on a product that would have sold well, and blaming the product rather than the timing leads to the wrong buying decision next season.

How to act on this

Set a target weekly rate rather than a period target, so products can be compared regardless of when they landed. Anything below the target at the four-week mark gets a decision: promote, reprice, or mark down, while there is still season left to sell into.

Then feed it back into buying. Sell-through by product, by supplier and by category is the most direct evidence available about which buying decisions were good, and it is available long before the season ends.

Sell-through as an early markdown signal

The value of sell-through is that it produces an answer early. Four weeks into a twelve-week season, the weekly rate already predicts where the stock will end up, and acting then costs far less than acting at week ten.

The arithmetic: at week four with 30% sold, the projected end-of-season position is 90% sold, fine. At 15% sold, the projection is 45%, meaning more than half the buy will be left over, and a 20% markdown now will clear it where a 50% markdown in week ten might not.

This is the single strongest argument for tracking sell-through weekly rather than reviewing stock quarterly. The information that lets a small markdown work is available months before the information that forces a large one, and the difference between the two is usually the difference between a profitable season and a flat one.

It is worth calculating sell-through by supplier and by buyer, not only by product. Patterns show up at that level that individual products hide, one supplier whose products consistently underperform, or one buyer whose enthusiasm systematically outruns the demand.

Those patterns are the most valuable output of the measurement, because they change future decisions rather than only the disposal of current stock.