How to Calculate Reorder Points for Shopify SKUs

A reorder point tells you when to buy before a SKU stocks out. For a small Shopify store, the formula does not need to be complex. It needs to be consistent, explainable, and tied to supplier lead time.

The simple reorder point formula

Reorder point = lead time demand + safety stock.

Lead time demand is the number of units you expect to sell while waiting for a supplier shipment. If a SKU sells 4 units per day and the supplier usually takes 10 days, lead time demand is 40 units.

Safety stock is the buffer for late suppliers, demand spikes, or receiving delays. A practical starting point is 20% to 50% of lead time demand for steady SKUs, and more for seasonal or promotion-sensitive products.

Example

• Average daily sales: 4 units
• Supplier lead time: 10 days
• Lead time demand: 40 units
• Safety stock: 15 units
• Reorder point: 55 units

What to review before trusting the number

Check whether the SKU is seasonal, whether the supplier ships in case packs, whether inventory is split across multiple Shopify locations, and whether recent sales are distorted by discounts. Reorder math is only useful if the SKU, supplier, and cost data are clean.

How incoming POs change the recommendation

A forecast should not recommend buying 40 more units if 40 units are already on an open PO. Good reorder logic subtracts incoming units, respects pack size, rounds to supplier MOQ, and keeps the PO open until the shipment is fully received or rejected.

How confidence should affect buying

A high-confidence forecast usually has clean SKU history, a stable supplier, known lead time, and enough sales days to estimate velocity. A low-confidence forecast might still be useful, but it should be treated as a prompt to review the SKU rather than an automatic purchase order. For a new SKU, use a manual minimum quantity until enough sales history exists.

Low confidence example

If a SKU sold 30 units during a one-week promotion and then only 2 units per week afterward, a naive forecast will overbuy. Mark the forecast low confidence, review promotion context, and set a conservative reorder rule until the sales pattern stabilizes.

Do not ignore overstock

Reorder workflows often focus only on stockouts, but overstock ties up cash and warehouse space. Overstock SKUs should be reviewed for pause buying, transfer, markdown, bundle, return-to-vendor, or hold workflows. The correct action is usually not another PO; it is a liquidation or demand-shaping plan.

Weekly reorder review process

1. Review urgent and stockout risk first.
2. Check incoming POs before creating a duplicate supplier order.
3. Pause buying for overstock SKUs that should not appear in draft POs.
4. Create supplier-grouped PO drafts only after supplier costs and pack sizes look correct.
5. Receive partial shipments as they arrive so forecasts use the current incoming balance.

Vamao Inventory OS flags SKUs with missing reorder points, low inventory, missing supplier costs, weak supplier mappings, urgent stockout risk, and overstock risk so you can fix the operational data before relying on automated purchase recommendations.