How to use it
- Choose how you measure the shelf: facings or centimetres. Enter the total space the category has on the planogram.
- Choose whether sales are in value or units, then add one row per brand or SKU with its category sales for the same period.
- Enter the space each row holds today, in the same measure as the total.
- Leave the minimum per row on if no listed item should drop off the shelf, and set how many facings or centimetres that minimum is.
- Switch on the strategic adjustment only for rows you have a stated reason to back or trim, such as a launch.
- Read the table: fair space, the difference from today, and the space-to-sales index. Start the conversation with the rows furthest from 100.
How fair share of shelf works
A common category management principle is that shelf space should track sales share. The shelf is the pharmacy’s scarcest selling asset, and space given to a slow seller is space taken from a fast one. So the first draft of a planogram shares the shelf out in proportion to each brand’s share of category sales. That is what this calculator does first: sales share times total space.
The first draft is then adjusted for three things. Strategy: a launch, or a brand the category plan has chosen to grow, may get more than its sales history would earn, and something else gives up that space. Minimum facings: an item that is listed needs enough presence to be found and to hold stock between deliveries. Shopper navigation: the shelf has to be laid out the way shoppers look for the category, by need, by form or by brand, and that can move space between rows. The calculator handles the first two with numbers; the third is a judgement you make on the planogram itself. For worked layouts, see the pharmacy planogram guide and the planogram examples.
The strategic adjustment multiplies a row’s sales share by your percentage (for example +20% turns a 10% share into a 12% weight), then scales every weight back so they add up to 100%. The minimum per row lifts any row below the floor up to it and shares the rest of the shelf among the others by weight. Facings are then rounded to whole numbers so the total always matches the shelf you entered.
Limits of the method
- It looks backward. Sales share reflects the space a brand already had, so an under-spaced brand may be under-selling because it is under-spaced.
- It ignores margin. A row with a modest sales share can still earn its space through profit; weigh that in the category review.
- It ignores pack size. A facing of a wide pack takes more shelf than a facing of a slim one, so check centimetres as well as facings when packs differ a lot.
- It does not know about stock. Check that the fair-share facings can hold enough stock to last between deliveries.
- It is one category on one shelf. Space between categories is a separate decision.
Once the new planogram is agreed, the work moves to the store. The planogram compliance checklist covers how to check it is actually on the shelf, and the category management guide puts shelf space in the wider category plan.
Frequently asked questions
What is fair share of shelf?
Fair share of shelf is the idea that each brand or SKU should hold roughly the same share of the shelf as it holds of the category's sales. If a brand brings in a third of the category's sales, it starts with about a third of the space. It is a starting point for a planogram, not the final answer, because strategy, minimum facings and how shoppers find their way around the shelf all move it.
Should I use sales value or units sold?
Use value when the question is which brands earn the shelf, because it reflects price as well as volume. Use units when the question is replenishment, because a fast-moving low-price item can run out of stock on a small facing even if its value share is modest. Many teams look at both and settle somewhere between them. The calculator works the same way with either.
What does the space-to-sales index mean?
It is the row's share of current space divided by its share of sales, multiplied by 100. An index of 100 means space and sales are in line. Above 100, the row holds more shelf than its sales earn; below 100, it holds less. It is a quick way to spot the rows that deserve a closer look in a category review.
How does the calculator round to whole facings?
It rounds every row down to a whole facing, then hands out the facings left over one at a time to the rows with the largest fractions. This is the largest-remainder method, and it means the fair-share facings always add up to exactly the total shelf space you entered. If you switch on a minimum per row, the minimum is applied first and the rest of the shelf is shared out by sales.
When should I not follow the fair-share number?
When there is a clear reason to invest or protect: a launch with no sales history yet, a brand the category plan has chosen to grow, a slow-moving item shoppers still expect to find, or a pack that physically needs more width. The strategic adjustment and the minimum per row are there for those cases. Write down the reason for every departure so the next review can check whether it paid off.
Taking the shelf into a category review? The category review pack in the planning kit gives you the slides for the review itself: what moved, why, and what you are asking for. Or join the community and tell us which calculator to build next.