How is the monthly storage fee calculated ?

How is the monthly storage fee calculated ?

AZInsight calculates the monthly storage based on the data provided by Amazon. The fees are calculated based on the Product size tier, the volume of the product, the number of days the product is in Amazon's warehouse, and if the product is hazmat or not.  Amazon routinely changes these fees and you can always verify them using the official Amazon Revenue Calculator 

The fee structure for 2024 can be found here US referral and FBA fee changes summary.