Suppliers are late. Demand spikes unexpectedly. Shipments get held at customs.
These things happen. Safety stock is what keeps you selling when they do.
What is safety stock?
Safety stock is extra inventory you keep on hand above your expected needs. It is a buffer — a cushion against two things:
- Demand variability — you sell more than expected in a short period
- Supply variability — your supplier takes longer than usual to deliver
Without safety stock, any unexpected event turns into a stockout.
The simple safety stock formula
There are complex statistical formulas for safety stock, but for most Shopify merchants, this version works well:
Safety Stock = Average Daily Sales × (Maximum Lead Time − Average Lead Time)
Example
- Average daily sales: 5 units
- Average lead time: 14 days
- Maximum lead time you have experienced: 21 days
Safety Stock = 5 × (21 − 14) = 5 × 7 = 35 units
Keep 35 extra units on hand as your buffer.
How much safety stock is right for your store?
The right amount depends on two things:
How variable is your demand? If your sales are very consistent day-to-day, you need less safety stock. If you have big swings — seasonal spikes, flash sales, viral moments — you need more.
How reliable is your supplier? A supplier who always delivers on time needs a smaller buffer than one who regularly runs late.
The cost of getting it wrong
Too little safety stock means stockouts. A stockout is not just a missed sale — it can damage your search rankings on Google, drop your Shopify store’s conversion rate, and push customers to a competitor.
Too much safety stock ties up working capital. That cash could be used for marketing, product development, or simply sitting in your bank account.
Set it once, then let IFH maintain it
Inventory Forecasting Hero lets you set a safety stock level per product. Once set, it factors that buffer into every reorder calculation automatically — so you are always ordering the right amount without having to recalculate by hand.
Inventory Forecasting Hero does this automatically for your Shopify store. From $25/month.
Start Free Trial →