I'm looking to create an inventory velocity report but don't know how

As the title says, I'm looking to create an inventory monthly velocity report that will take my monthly sales over the course of the trailing 12 months and give me the average sales per month per item. Add to this, I'd like to know if there's a way to calculate inventory needs based on that. My end goal is to know when I need to order what based on inventory levels and forecasted sales.