Sell-through rate and inventory ageing: the two numbers a fashion brand should see every week
Sell-through is units sold after returns divided by units received, multiplied by one hundred. Inventory ageing and weeks of cover add context. Compare articles over the same period, per size and colour, against your own season plan. A percentage only becomes useful when the target, period and replenishment policy are stated.
The formula, and the trap inside it
Sell-through (%) = units sold ÷ units received × 100
A style received in 300 units with 240 net units sold has a sell-through of 80 percent. Deduct actual returns. Calculate per size and colour: an average per style can conceal broken size runs.
Set targets per category
Use your own season plan, margin and replenishment policy. Compare the same period and category, and distinguish full-price sales from discounted sales. The calculator target is an editable example, not a validated industry benchmark.
| Category | Measurement period | Compare with |
|---|---|---|
| Seasonal fashion (outerwear, prints, occasion wear) | The same stage of the season | Your own plan, margin and prior comparable periods |
| Basics and underwear (continuous range) | A fixed period with receipts included | Your own plan, margin and prior comparable periods |
| Sport and outdoor | The same season and replenishment policy | Your own plan, margin and prior comparable periods |
| Footwear | Per size and colour over the same period | Your own plan, margin and prior comparable periods |
Seasonal fashion (outerwear, prints, occasion wear)
- Measurement period
- The same stage of the season
- Compare with
- Your own plan, margin and prior comparable periods
Basics and underwear (continuous range)
- Measurement period
- A fixed period with receipts included
- Compare with
- Your own plan, margin and prior comparable periods
Sport and outdoor
- Measurement period
- The same season and replenishment policy
- Compare with
- Your own plan, margin and prior comparable periods
Footwear
- Measurement period
- Per size and colour over the same period
- Compare with
- Your own plan, margin and prior comparable periods
The benchmark says less than your own trend. A style at 35 percent halfway through a season with an 80 percent target is already behind the pace it needs. That is the moment to act, not the week before the sale.
Inventory ageing: the second number
Measure ageing in days since the last sale per article, or in weeks of cover: current stock divided by the average weekly sales of the last eight weeks. Rules of thumb for fashion:
| Cover | Status | Action |
|---|---|---|
| Under 8 weeks | Healthy | Consider reordering the sizes that sell |
| 8 to 20 weeks | Slow | Marketing or markdown in your own channel; check the size run |
| 20 to 52 weeks | Critical | Bundle or sell as a lot before the season turns |
| Over 52 weeks, or no sale in 180 days | Dead | Sell as a lot, donate or recycle |
Under 8 weeks
- Status
- Healthy
- Action
- Consider reordering the sizes that sell
8 to 20 weeks
- Status
- Slow
- Action
- Marketing or markdown in your own channel; check the size run
20 to 52 weeks
- Status
- Critical
- Action
- Bundle or sell as a lot before the season turns
Over 52 weeks, or no sale in 180 days
- Status
- Dead
- Action
- Sell as a lot, donate or recycle
And count inbound orders. An article that looks healthy today with a container still on the water is a problem in eight weeks. Include inbound in the cover (economic stock), so you can still cancel or reduce before the goods arrive.
Per system: where the number lives and what is missing
| System | What it has | What is missing | How to get it |
|---|---|---|---|
| Shopify | Sales per variant, stock per location, sell-through and ABC analysis on the product page, days in stock | Cost per item often empty, no B2B sales, no warehouse count | Fill in cost per variant; export sales per variant over 52 weeks; set stock beside it |
| Itsperfect | Cost price, purchase orders, B2B and retail sales, landed cost | Exact stock on the shelf when a 3PL runs the warehouse | Report sales per article per week plus a stock list; EAN as the key |
| Exact Online | Stock value and write downs in the books | Sales velocity per size and colour | Only for the financial side; combine with webshop or ERP |
| Monta or another 3PL | What is actually on the shelf, per EAN, including inbound | Sales data and cost price | Stock export per EAN; this is the only count that is right |
| Picqer | Stock and orders from several channels | Cost price sometimes, B2B usually | Export per product; join to the ERP for cost price |
Shopify
- What it has
- Sales per variant, stock per location, sell-through and ABC analysis on the product page, days in stock
- What is missing
- Cost per item often empty, no B2B sales, no warehouse count
- How to get it
- Fill in cost per variant; export sales per variant over 52 weeks; set stock beside it
Itsperfect
- What it has
- Cost price, purchase orders, B2B and retail sales, landed cost
- What is missing
- Exact stock on the shelf when a 3PL runs the warehouse
- How to get it
- Report sales per article per week plus a stock list; EAN as the key
Exact Online
- What it has
- Stock value and write downs in the books
- What is missing
- Sales velocity per size and colour
- How to get it
- Only for the financial side; combine with webshop or ERP
Monta or another 3PL
- What it has
- What is actually on the shelf, per EAN, including inbound
- What is missing
- Sales data and cost price
- How to get it
- Stock export per EAN; this is the only count that is right
Picqer
- What it has
- Stock and orders from several channels
- What is missing
- Cost price sometimes, B2B usually
- How to get it
- Export per product; join to the ERP for cost price
That is the core of the problem: no single system holds all three numbers (sold, cost, on the shelf). Unworn's free analysis reads all three and joins them on EAN, so sell-through, ageing and weekly cost sit per article in one view, with what each article is likely to return per route.
ShopifySee the integration
ItsperfectSee the integration
MontaSee the integration- Exact OnlineSee the integration
- PicqerSee the integration
Frequently asked questions
Use your own season plan, margin and replenishment policy. Compare the same period and category, and distinguish full-price sales from discounted sales. The calculator target is an editable example, not a validated industry benchmark.
Sell-through measures one buy over one period (how much of what came in has sold). Inventory turnover measures how often your total stock is sold and replaced per year (cost of goods sold divided by average inventory). Sell-through is the number to steer on during the season.
Weekly per article during the season. The end of season figure is a report card; the weekly pace is the number you can still act on.
Not as a separate report. Shopify shows sell-through, ABC analysis and days in stock on the product page and in inventory reports, but without cost price and without a warehouse count the picture stays incomplete.
Physical stock plus inbound orders minus open sales orders. That is the number to decide on, because it shows what will be on the shelf in eight weeks, not what is there now.