Hold just enough buffer to never stock out.

There are several methods, but a common and intuitive one uses the gap between your worst case and your average: safety stock equals maximum daily usage times maximum lead time, minus average daily usage times average lead time. That difference is the extra stock you need to cover a demand spike arriving at the same time as a supplier delay. More statistical methods use a service-level target and the variability of demand and lead time, but the max-minus-average approach is a solid, transparent starting point that this calculator uses.

Too little safety stock and you risk stockouts — lost sales, disappointed customers, and rushed expensive reorders — whenever demand runs hot or a supplier is late. Too much and you tie up cash in inventory that sits on the shelf, absorbing storage cost and risking obsolescence. Safety stock is a deliberate balance between those two costs, set higher for items where a stockout is costly or supply is unreliable, and lower for steady, easily replaced items. The planner lets you set it per SKU so the buffer matches each item's risk.

A ready-to-use spreadsheet (Excel & Google Sheets): safety stock and reorder points for every SKU from your usage and lead-time inputs — delivered instantly after checkout. AI-assisted, human-built; not financial advice.