Safety stock

Safety stock is the extra stock you hold beyond expected demand, so a sudden rise in sales or a late delivery does not leave you out of stock.

By Berend Vrakking, founder of Product Metrics. Updated 7 October 2026.

Formula

Safety stock = days of extra cover × average daily demand

This is one common method, not the only one. Others use the spread of demand and of lead time, or the gap between the highest and the average daily sales. The days of cover are your choice.

Example

Worked example, three products
Product	Average daily demand	Days of extra cover	Safety stock
Trail Runner 2	20 units	5 days	100 units
Winter Boot	4 units	7 days	28 units
Everyday Sock	60 units	3 days	180 units

Each product gets its own cover, so Trail Runner 2 holds 20 × 5 = 100 units of safety stock. This stock is not for the expected demand. It sits untouched until demand or delivery goes off plan. Illustrative data.

For one product, and for an account

A product whose sales swing from day to day, or whose supplier is often late, needs more cover than a steady product with a reliable supplier. One number of days for the whole shop leaves some products short and ties up money in others.

Inventory Insights calls this the safety buffer. It uses the buffer, with projected demand and the supplier lead time, to work out a reorder date for each product.

Common mistake

Picking a formula and never checking it against what happened. How much demand and lead time vary for a product decides which method suits it, and its stockouts and untouched buffers tell you whether you chose well.

Questions

What is another name for safety stock?

Safety stock is also called buffer stock. Inventory Insights uses the term safety buffer for the same idea: the stock you never want to dip below.

What is a good safety stock level?

Enough to cover the demand and delivery variation you actually see for that product, and no more, so money does not sit in stock that never sells. Your past stockouts and the products that gathered dust on the shelf show which way to move it.

Is safety stock the same as minimum stock?

Not necessarily. Safety stock is the extra units held against variation. The reorder point is the level that triggers an order, and it includes safety stock. “Minimum stock” is used for different things in different businesses, so check which level a person means.

Keep reading

Reorder pointSafety stock is added to demand during the lead time.
Lead timeA longer lead time leaves more room for demand to run above plan.
StockoutThe event that safety stock is held to prevent.
Inventory InsightsSee the safety buffer in each product’s reorder date.
Dead stock inventoryWhere a safety buffer ends and stock that will not sell begins.