Why safety stock is not wasted money

It covers variation, not guesswork

Sales are never perfectly flat. Some weeks are slower, some faster, and suppliers do not always ship on the exact day they promised. Safety stock is the buffer that absorbs that variation so a late delivery or a busy week does not turn into an empty shelf.

The cost of a stockout is usually bigger than the cost of a few extra units

Holding a handful of extra units costs you some cash tied up and maybe a bit of storage space. Running out costs you the sale itself, and often the next sale too, because the customer buys elsewhere and may not come back. For a product that is part of a bigger order or a repeat purchase, a stockout can cost more than months of carrying a small buffer.

It is a dial, not a fixed cost

Safety stock does not have to be large. You set it in days, and you can set it differently per SKU. Fast, critical sellers can carry a few more safety days. Slow or low-risk items can carry almost none. The point is to size the buffer to the actual risk, not to hoard stock everywhere.

Too little safety stock is its own hidden cost

Cutting safety stock to save cash often just moves the cost somewhere else: rush shipping fees, split orders, or lost sales while you wait for the next delivery. A small, deliberate buffer is usually cheaper than reacting to a stockout after it happens.

Step by step

1. List your best sellers and rank them by how badly a stockout would hurt sales or reputation.
2. Check each supplier's lead time reliability, including how often they ship late.
3. Set more safety days for products with unreliable suppliers or spiky demand.
4. Set fewer or zero safety days for slow movers or products with backup suppliers.
5. Recalculate reorder points using daily sales x (lead time + safety days).
6. Review safety day settings every few months as supplier performance or demand patterns change.
7. Track stockouts you do have and ask whether more safety stock would have prevented them.

Worked example

A store sells a candle at 6 units a day. The supplier's lead time is 10 days, and deliveries sometimes run 3 days late, so the store sets 3 safety days. Reorder point = 6 x (10 + 3) = 78 units. Without the safety days, the reorder point would be 60 units, and a 3-day late shipment would mean roughly 18 units of lost sales before restock. The extra 18 units of safety stock cost far less to hold than the sales and customers lost from running out.

How SteadyShelf helps

SteadyShelf lets you set safety days per SKU and per supplier, and it builds that into the reorder point and order-by date automatically, so you do not have to recalculate the buffer by hand. It does not model stockout cost or tell you exactly how many safety days to use for a given risk level, that judgment call is still yours.

$29/month flat, unlimited products and suppliers, 30-day free trial. Run the numbers now with the free reorder point calculator.

SteadyShelf is launching on the Shopify App Store. Join early access to get the install link first.

Related guides

• Why simple forecasts often beat complex ones
• Why you have too much inventory
• Why you keep running out of stock
• Why lead time matters more than you think

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