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Safety Stock Calculator

Calculate the right buffer stock to protect against demand spikes and supplier delays. Free, instant.

Free
Formula: Safety Stock = Z × σ(demand) × √(lead time)  |  Or use our simplified version below.
Your highest sales day in the past 90 days
Longest your supplier has ever taken
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Frequently asked questions

What is safety stock?

Safety stock is extra inventory held as a buffer against unexpected demand spikes or supplier delays. It's the difference between running out of stock and staying in business through supply chain disruptions.

How much safety stock should I hold?

It depends on the variability of your demand and supplier lead times. Higher variability = more safety stock needed. The simple method above (max demand - average demand) is a good practical starting point for most Shopify merchants.

Is holding safety stock expensive?

There's a cost to holding excess inventory (typically 20–30% of inventory value annually for carrying costs). But the cost of a stockout — lost sales, customer churn, ad waste — almost always exceeds the carrying cost of safety stock.