In this article we will explore the Stock Days strategy and how it can give you an easy way to understand how much stock you wish to hold when the lead times are a variable to consider. 

If your products loaded into the modelling grid have varying lead days, then consider using the Just-in-Time strategy, as the lead days are factored in, with buffers to calculate the number of days of stock you want to hold per product. 

Stock days works simply by take the days of stock you want to hold directly, and calculating this against each product / warehouse rate of demand. 

Here's what the interface looks like when clicking the Stock Strategy button in the Modelling tab:

If we take another simple example of a group of products you want to hold up to 30 days of stock for, and you want to reorder more stock when you have 7 days of stock remaining, then you will simply enter the min days of stock as 7 and the max days of stock as 30:

If a product has less than 7 days as a lead time, then the difference will be your buffer time to place an order, or assemble more stock before you are at risk of stock arriving too late. If a product has a lead time of more than the 'Min days of stock' value, then you are likely reorder more stock and have a stock out (on average) before this stock arrives. You will need to ensure that you set the 'Min days of stock' to be greater than the lead days of the products you are modelling (or as stated, use the Just-in-Time strategy that caters for variable lead times).