Buffer Stock
The cushion of extra stock that absorbs demand and supply swings.
Definition
Buffer stock is extra inventory held to absorb unexpected swings in demand or supply, protecting you from stocking out when sales spike or a shipment runs late. It is often used interchangeably with safety stock; both are the cushion above your expected need, sized to the variability you face.
Buffer stock vs safety stock
In everyday use the two terms are synonyms, and most sellers and software use them interchangeably. Some frameworks try to separate them by purpose, but there is no single agreed definition, so do not get attached to one. For an FBA seller the practical question is identical either way: how much cushion do you hold, and is it sized to the variability you actually experience.
Why FBA sellers need a buffer
FBA lead times are long and multi-leg, Amazon check-in adds a variable delay, and demand can spike on a deal or a seasonal swing. Without a buffer, those normal fluctuations line up at the worst moment and you stock out during exactly the window you most wanted inventory.
How to size buffer stock without overstocking
More buffer is not free. It ties up cash, racks up storage fees, and drags your IPI by inflating your excess-inventory ratio. Size it to each SKU's demand variability and lead-time variability instead of defaulting to a round number of weeks that is too much for steady sellers and too little for spiky ones.
Related terms
Size your buffer per SKU, not by the week
Inventory Hero sets each product's cushion from its real demand and lead-time variability, so you hold enough to stay in stock without dragging your IPI.