How to Set Reorder Points in Shopify Before You Run Out of Stock

What is a reorder point?

A reorder point (ROP) is the minimum inventory quantity that triggers a new purchase order. When your on-hand stock drops to this number, you place a reorder — so the new shipment arrives before you hit zero. Get it right and you never stockout. Get it wrong and you're either out of stock losing revenue, or sitting on excess capital tied up in slow-moving inventory.

The standard formula:

Worked example: You sell a skincare serum that moves 15 units per day on average. Your supplier in South Korea takes 12 days to deliver (including customs). You want 60 units of safety stock to cover unexpected demand spikes or shipping delays.

ROP = (15 × 12) + 60 = 240 units. When your inventory hits 240, you place the next purchase order. The shipment arrives in 12 days with inventory to spare.

Why Shopify's native inventory tools aren't enough

Shopify gives you a live count of on-hand inventory for each variant and lets you enable "out of stock" product hiding. That's essentially the full extent of native inventory intelligence. There are no low-stock alerts, no reorder point fields, no velocity tracking, and no forecasting based on sales history.

In practice, Shopify merchants default to one of two bad habits: checking inventory manually every week (time-consuming and error-prone), or waiting for the dreaded "oversold" notification after a customer placed an order on a product you didn't actually have. Both approaches are reactive. Reorder points are the shift to proactive inventory management.

The other gap is forecasting. Shopify's analytics show you historical sales but don't project forward. A reorder point based on last month's average daily sales works fine for steady-state products but breaks down for seasonal items with a 4x demand spike in December.

How to calculate your safety stock

Safety stock is the buffer inventory you hold to absorb two types of uncertainty: demand variability (you sell more than expected) and supply variability (your supplier ships late). The right safety stock level depends on your product and risk tolerance.

The 20–30% buffer rule is a reasonable starting point for most products. If you've experienced a stockout in the last 12 months, treat that as a signal to increase your safety stock — the cost of holding extra inventory is almost always lower than the cost of a stockout (lost revenue, emergency shipping fees, customer churn).

Setting reorder points for seasonal vs. evergreen products

Evergreen products with consistent demand are straightforward: calculate 90-day average daily sales, multiply by lead time, add your safety stock buffer, and set that as your reorder point. Review it quarterly.

Seasonal products need a different approach. A single ROP doesn't work across the full year — the threshold that protects you in December will leave you dramatically overstocked in February. Here's the approach:

• Off-season ROP: Use your lowest 4-week rolling average daily sales × lead time + minimal safety stock (10–15%). You're covering basic replenishment, not a surge.
• Pre-season ROP: Increase your ROP 4–6 weeks before peak season using last year's peak sales data. If Q4 sales are 3x your Q2 baseline, your ROP should reflect that multiplier.
• In-season ROP: Switch to a shorter rolling window (14-day average) to capture the actual in-season velocity rather than relying on last year's numbers, which may not account for year-over-year growth.

The simplest calendar approach: set two ROP values per seasonal SKU — one for high season, one for low season — and update them on a schedule. Most merchants forget to do this update and end up with the wrong threshold active when it matters most.

How EZStock automates reorder alerts

EZStock adds the reorder point functionality that Shopify doesn't include. You set a reorder threshold for each SKU in the EZStock dashboard. The app then tracks your actual inventory levels in real time by syncing with Shopify's inventory API.

The 30-day velocity calculation runs automatically: EZStock looks at your last 30 days of Shopify orders for each SKU, calculates average daily sales, and projects how many days of stock you have remaining at the current burn rate. When the projected days of stock drops below your threshold — or when inventory crosses your set reorder point — you get an email alert with the product name, current stock level, and the suggested order quantity based on your lead time setting.

For purchase orders, EZStock takes the next step: when a reorder alert fires, you can open the PO creation screen from the alert email, pre-populated with the triggered SKU, quantity, supplier, and cost price. It turns a passive alert into an active workflow.

Common reorder point mistakes

The most common error is setting ROP too low — calculating only lead time demand without safety stock, assuming everything will go exactly to plan. Suppliers ship late. Demand spikes. A storm delays a container. Safety stock exists for the gap between plan and reality. Never set an ROP that leaves zero buffer.

The second mistake is ignoring lead time variance. If your supplier usually takes 10 days but sometimes takes 18, your ROP should use 18 days as the lead time, not 10. Using the best-case lead time means you'll stockout every time the supplier has a bad week.

Third: not updating ROPs after changing suppliers. If you switch from a domestic supplier with a 5-day lead time to an overseas supplier with a 21-day lead time and forget to update your thresholds, every reorder point in your store is now wrong by a factor of four.