# Weeks of cover

Weeks of cover is how long current stock will last at the expected rate of sale: stock on hand divided by forecast weekly sales.

Also called: stock cover, days of cover

- **Measures:** How long current stock lasts at the expected rate of sale.
- **Formula:** Units on hand ÷ expected units sold per week.
- **Watch for:** A rate of sale inflated by a promotion or deflated by a stockout.

## What it means for retail and category teams

Some teams use days of cover instead, and some include stock on order. Cover puts stock and demand in the same unit, which is why availability, allocation and markdown decisions are often set in weeks of cover. The rate of sale behind it matters: a recent promotion inflates it and a recent stockout deflates it, so a cover figure is only as reliable as the demand estimate underneath.

## Why it matters

Too little cover means missed sales; too much ties up cash and space and raises the risk of markdown. Comparing cover across locations shows where moving stock can fix availability before anyone orders more.

## Illustrative example

The business and figures are illustrative. None of it is customer data.

A kettle sells 8 a week in Store A, which holds 12: 1.5 weeks of cover. Store B sells 3 a week and holds 30: 10 weeks. Moving 10 units from B to A gives A 22 units, about 2.8 weeks, and leaves B with 20, about 6.7 weeks. Store A avoids a gap before its next delivery, and the business holds no more stock than before.

**One kettle in two stores**

| | Cover now | Cover after moving 10 units | Result |
| --- | --- | --- | --- |
| Store A (12 on hand, sells 8 a week) | 1.5 wks | 2.8 wks | Gap closed |
| Store B (30 on hand, sells 3 a week) | 10 wks | 6.7 wks | Still covered |

Ten units moved, no new stock bought, and both stores have more than two weeks.

## Calculate weeks of cover

Weeks of cover = usable units on hand ÷ expected units sold per week

This simple cover figure excludes stock on order and delivery lead time.

[Use the calculator](https://twelfth.ai/tools/weeks-of-cover), [explore the worked examples](https://twelfth.ai/tools), [download the Excel / Google Sheets workbook](https://twelfth.ai/resources/retail-metrics-template.xlsx) or [download this metric's CSV template](https://twelfth.ai/resources/retail-csv/weeks-of-cover.csv).

## Related concepts

- [Stockout](https://twelfth.ai/glossary/stockout): Check for lost sales if the recent sales rate was held down by unavailable stock.
- [Stock transfer](https://twelfth.ai/glossary/stock-transfer)
- [Demand forecast](https://twelfth.ai/glossary/demand-forecast)
- [Replenishment](https://twelfth.ai/glossary/replenishment): Add lead time and safety stock to see whether the line has reached a reorder point.

## Next step

### See where cover needs attention

A single cover number is a start. Bring a product and its locations to look at demand, stock and possible transfers together.

- [Book a demo](https://twelfth.ai/book-a-demo)
- [twelfth for merchandise planners](https://twelfth.ai/for/merchandise-planners): Continuous demand, cover and flow monitoring that shows where the buy plan and the actual trade have come apart.

Source: https://twelfth.ai/glossary/weeks-of-cover