The sell-through rate calculator above answers a buyer’s question rather than an accountant’s: of the units that came in, how many went out again in the period? It computes that on both of the definitions in common use, reports what is left, converts the leftover into weeks of supply at the rate things are actually selling, and values it at cost so the number stops being abstract.
Arb Digital works with retailers and product businesses where buying decisions and marketing spend compete for the same cash. Sell-through is the metric that tells you whether a buy was the right size, and it does that faster than any accounting ratio, because it works in units and needs only a fortnight of data to say something useful.
What This Sell-Through Rate Calculator Does
It runs two sell-through figures. The first divides units sold by units received in the period, which measures the buy: did we order the right quantity for the demand that turned up? The second divides units sold by units available — opening stock plus receipts — which measures the whole position, including what was already sitting there. Neither is more correct than the other; they answer different questions, and the mistake is only ever mixing them.
Around that, units remaining is the arithmetic residue, weeks of supply converts it into time at the observed selling rate, and the value at cost is what is still tied up. A target you set yourself is compared against the headline figure, and the tool reports how many more units would have had to sell to reach it.
A boundary with the closest live tool. Our inventory turnover calculator is an accounting ratio: cost of goods sold divided by average inventory, over a whole business or category, expressed in turns per year. This page works in units, over a defined period, against receipts rather than an average, which is why it can evaluate a single buy of a single style weeks after it landed — something turnover cannot do until the year is well advanced. The reorder point calculator sits downstream of both: sell-through tells you how a buy performed, the reorder point tells you when to raise the next order.
How to Use It
- Enter opening stock and units received. Keep both for one product or one style — sell-through averaged across a whole category hides exactly the lines you would want to see.
- Enter units sold, net of returns that went back into saleable stock.
- Set the length of the period in weeks. The rate is meaningless without it, because 60 per cent in two weeks and 60 per cent in six months are opposite results.
- Set your own target from your buying plan. There is no universal benchmark and this page does not pretend otherwise.
- Read weeks of supply alongside the percentage. That is the number that tells you whether to reorder, hold or mark down.
The Formula and How It Is Calculated
Two denominators, one numerator:
Sell-through (received basis) = Units sold ÷ Units received × 100
Sell-through (available basis) = Units sold ÷ (Opening stock + Units received) × 100
Weeks of supply is units remaining ÷ (units sold ÷ weeks in period), which is simply how long the leftover lasts at the rate observed.
Work through the defaults. Opening stock of 120 and 480 received gives 600 units available, of which 390 sold in four weeks. On the received basis that is 390 ÷ 480 = 81.25 per cent. On the available basis it is 390 ÷ 600 = 65.00 per cent. The gap between the two is entirely the opening stock, and quoting one while thinking of the other is the single most common error in this metric.
Units remaining are 600 − 390 = 210. Sales are running at 390 ÷ 4 = 97.5 a week, so the remainder is 2.2 weeks of supply — about 15 days. At a unit cost of 12 that leftover is 2,520 of stock at cost, and the 390 units sold at a 30 price against a 12 cost produced 7,020 of gross margin. Against an 85 per cent target on the received basis, 408 units would have had to sell, so the buy fell 18 units short.
Why the Denominator Argument Matters
Both definitions are used in real businesses and both appear in software. A vendor evaluating a retailer wants the received basis, because it isolates what happened to the units they shipped. A store manager wants the available basis, because they have to clear everything on the floor regardless of when it arrived. Neither is wrong.
What is wrong is switching between them, which happens constantly and always in a flattering direction. A line with old stock behind it looks far better on the received basis, because the denominator excludes the units that have been sitting there since spring. If a buyer quotes 81 per cent and the shop floor is looking at 65 per cent, nobody is lying and nobody is talking about the same thing.
Two disciplines fix it. Pick one basis per report and label it in the column heading rather than in a footnote. And never compare a sell-through figure against another without checking that the periods are the same length — a percentage with no time attached is not a rate at all, which is why this tool refuses to report one without a period.
Reading the Number Against Time
Sell-through is most useful early. Four weeks into a twelve-week season, a line at 70 per cent of its receipts is going to run out and needs a reorder or a substitute; a line at 15 per cent is going to end the season with most of the buy intact and needs a decision about markdown timing while there is still traffic to sell into. Both conclusions are available in week four and neither is available from a year-end ratio.
That is why weeks of supply is the more actionable of the two outputs. A percentage says how the buy has gone; weeks of supply says what to do next. Under your lead time, you are going to stock out before a replacement lands, and the reorder point calculator is where that gets sized properly with a service level attached. Far above the remaining weeks of the season, the leftover is going to be a markdown, and the only question is when.
The caution is that both figures assume the observed rate continues, and it usually does not. Seasonal lines decay. Promoted lines spike and then fall back below their old rate, because a promotion pulls demand forward as well as creating it. A line whose sales are entirely from one large trade order has no run rate at all. If the period you measured contained a promotion, a stockout or a holiday, the weeks-of-supply figure is projecting from an unrepresentative fortnight, and our revenue forecast calculator is a better instrument for anything more than a short horizon.
What Sell-Through Cannot Tell You
A high rate is not automatically good news, and this is where the metric misleads people most often. Selling 100 per cent of a buy in three weeks means the buy was too small: the demand that arrived in weeks four to twelve was never served, and lost sales are invisible in every number on this page. A perfect sell-through with a stockout behind it is a worse outcome than 85 per cent with availability maintained.
Nor does it know anything about margin. Units cleared at half price still count as sold, so a heavily marked-down line can post an excellent sell-through and a poor contribution. Reading the percentage next to realised margin is the only way to catch that, which is what our profit margin calculator is for, and the GMROI calculator combines margin with the inventory investment directly.
It is also blind to the cost of holding what is left. Storage, capital, insurance and obsolescence all accrue against the remaining units, and none of it appears in a units-sold-over-units-received ratio. The EOQ calculator takes the holding-cost side seriously, and the COGS calculator and FIFO LIFO inventory calculator handle how the remaining stock is valued in the accounts — which matters, because the cost basis you use for the leftover is a formal accounting choice. In the United States the requirement to keep inventories at all is set out in the tax regulations at 26 CFR § 1.471-1, and the identification and valuation methods available — specific identification, FIFO, LIFO, lower of cost or market and the retail method — are set out in the IRS’s Publication 538 on accounting periods and methods. Sell-through is a management number and does not touch any of that, but the two have to be reconciled at year end.
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Browse the Free Tools Hub Talk to Arb DigitalCommon Mistakes to Avoid
- Quoting a percentage without a period. Sixty per cent in two weeks and sixty per cent in six months are opposite results. The time frame is part of the metric.
- Switching between the two denominators. Received basis and available basis give different answers, and the difference is exactly the opening stock. Pick one and label it.
- Reading a very high rate as success. Selling out early means the buy was too small and demand went unserved. Lost sales appear in none of these numbers.
- Ignoring markdowns. Units cleared at half price count as sold. A strong sell-through on a discounted line can sit alongside a poor contribution.
- Averaging across a category. A healthy category average routinely conceals one line selling out and another not moving at all. Run it per style.
Related Free Tools From Arb Digital
For the accounting view of the same stock, use the inventory turnover calculator, and the GMROI calculator to bring margin and inventory investment together. The reorder point calculator and EOQ calculator handle when and how much to order next, the COGS calculator and FIFO LIFO inventory calculator value what is left, and the profit margin calculator and revenue forecast calculator cover pricing and what comes next. Everything else is on the free online tools hub.
Frequently Asked Questions
Units sold divided by units received in the period, multiplied by 100. A second common definition divides units sold by units available, meaning opening stock plus receipts. Both are in general use and they give different answers, so the basis has to be stated whenever the figure is quoted.
There is no universal figure, which is why this page publishes none and takes the target as an input. What counts as healthy depends on the product life, the season length, the lead time for replenishment and the margin. A fast-moving staple and a twelve-week seasonal line are judged on completely different numbers.
Sell-through works in units over a defined period against receipts, so it can evaluate a single buy of a single style within weeks of it landing. Inventory turnover is an accounting ratio — cost of goods sold over average inventory — usually taken across a business or category and expressed in turns per year. They answer different questions at different speeds.
It depends on the question. Include it when you want to know how the whole position on the shelf performed, which is the store view. Exclude it when you want to isolate how a specific delivery performed, which is the buying and vendor view. The important thing is consistency between periods rather than which one you choose.
Units remaining divided by the average units sold per week during the period, giving the number of weeks the leftover would last if selling continued at the same rate. It is usually more actionable than the percentage, because it converts a result into a decision about reordering or marking down.
Not necessarily. Clearing every unit early means the buy was smaller than demand, so sales were lost after the stockout and no figure on this page can see them. A slightly lower rate with availability maintained through the season is frequently the better commercial outcome.
They should. If a returned unit goes back into saleable stock it has not sold, so netting returns out of units sold keeps the numerator and the stock position consistent. Counting gross sales against a net stock figure is the most frequent reason a sell-through calculation fails to reconcile with the stock on hand.
You can, but it hides the detail that makes the metric worth having. A category at a comfortable average routinely contains one line that sold out in week two and another that has not moved since it landed, and both need action in opposite directions. Run it per style and aggregate only for reporting.
This page performs arithmetic on figures you enter and publishes no benchmarks, prices or industry rates. It is not financial or accounting advice. How inventory is valued and reported in your accounts is a formal accounting matter governed by the rules of your jurisdiction and is a question for a qualified accountant.
