Inventory days

(Average inventory/Cost of sales) x 365days

Average inventory can be arrived by taking this year's and last year's inventory values and dividing by 2 - (Opening inventories+ closing inventories) / 2

This ratio shows how long the inventory stays in the company before it is sold. The lower the ratio the more efficient the company is trading, but this may result in low levels of inventories to meet demand.

A lengthening inventory period may indicate a slowdown in trade and an excessive build-up of inventories, resulting in additional costs.