How is the size curve calculated?

The size curve is calculated weekly automatically at store and section-family-size set level.

The size curve between stores can vary by up to 20%-25%. An accurate size curve calculation is mandatory to avoid significant over- or under- stocking of some sizes.

We use information from the product family to estimate applicable size curves of each product. Additional strategies are included to cover a potential lack of the right granular information.

Size curves are calculated once a week based on last 60 days sales and at different levels. You can request to change the number of days to calculate the size curve as needed.

Let's explain how the size curve is calculated with an example:

We have the following inputs:

• Product: P
• Family: Dress
• Size set of this product: XS, S, M, L
• Store: London

If the amount of sales of all the products (P,Q,R,S,T,...)  of this family (Dress) with this size set (XS, S, M, L) in the last 60 days(*) is:

More than 40 units sold in the London store: the size curve for product P is calculated at family- size set -store level.

Fewer than 40 units sold in the London store, but the sum of all the stores is over 40: the size curve for product P is calculated at family- size set -all stores level.

Fewer than 40 units sold adding all the stores: we take into account the sales of all the stores throughout the whole year.

Fewer than 40 units sold adding the whole year: we take the weights for each size for that family (without taking into account the sizeset) and, aggregate and normalize them.

(*)Taking into account all calculations as 60 days.