01 / Prepare
Build a useful baseline
Start with a single variant, such as a size and colour combination, rather than averaging every product together. Before calculating anything, bring these details into one place:
- The SKU or variant you are reviewing
- A recent average number of units sold per day
- Typical supplier lead time, from placing an order to receiving stock
- A safety buffer that reflects uncertainty and the cash you can hold in stock
- Your current count, plus any open purchase orders you need to account for
Use a consistent sales period and check whether unusual promotions, stockouts, or seasonal peaks make it unrepresentative. If your stock count is uncertain, do a physical count before using it as the starting point.
02 / Calculate
Set a reorder point for each variant
A reorder point is the stock level that tells you to review replenishment. A simple starting formula is average daily unit sales multiplied by supplier lead time, plus safety stock. Shopify’s guide describes this formula and explains each input in its reorder point guide.
The Supply Chain Resource Cooperative at NC State describes the underlying model as demand during lead time, with extra stock to protect against uncertainty in demand or lead time. Read its safety stock tutorial.
Illustrative example · sample numbers only
2 units/day × 12 days + 8 units = 32 units
With those assumptions, review a replenishment decision when that variant reaches about 32 units. The 8-unit buffer is a choice in this example, not a universal recommendation.
The threshold answers when to review an order; it does not decide how many units to buy. Set an order quantity separately using supplier pack sizes or minimums, expected demand, available cash, and storage space. Check open orders before placing another one.
03 / Gather data
Use Shopify reports as inputs
Shopify’s inventory reports include average units sold per day by product variant, a month-end inventory snapshot, and inventory adjustment history. Use the same variant and a period that reflects ordinary demand when you estimate sales velocity. The Shopify Help Center explains the inventory reports and their definitions.
Treat Shopify as the source for its own store data. A report in Shopify does not mean that another tool has received or refreshed the same data.
04 / Keep current
Review the assumptions, not just the threshold
Start with a weekly review of your important or fast-moving variants, then adjust the cadence to fit your order cycle. Revisit a reorder point after a promotion, a change in season, a supplier delay, or a material shift in demand. Shopify also recommends reviewing reorder points regularly and accounting for changes such as seasonality and shipping interruptions in its reorder point guidance.
- Check the current count and confirm the variant is the right one.
- Update the sales rate if the period no longer reflects typical demand.
- Confirm the supplier’s latest lead time and whether an order is already open.
- Compare the count with your threshold, then decide whether and how much to order.
- Record the decision and set a date for the next review.
05 / Merchandise Lens today
Where Merchandise Lens fits
Merchandise Lens is being built for small online shops across Canada. Product details, stock counts, and dated sales updates are entered by the shop owner. Shopify inventory sync is unavailable, so Merchandise Lens does not pull the reports described above or show them as live store data.
Merchandise Lens can save a supplier reorder draft for your review, but the draft is not emailed or sent to the supplier. For today’s workflow, read the FAQ. For the current offer, visit Pricing.
Sources
- Shopify Canada, “Reorder Point Formula: A Retailer’s Guide”
- Shopify Help Center, “Inventory reports”
- NC State Supply Chain Resource Cooperative, “Safety Stock Analysis”
Report definitions checked October 20, 2026.