Shopify Reorder Point Formula: When to Restock Before You Sell Out

A low-stock warning that appears when one unit remains is not a reorder system. If a Shopify product sells six units a day and the supplier takes 14 days, the next 84 units are already spoken for before a replacement carton can arrive. Add volatile demand and late shipments, and the useful warning may need to fire at 210 units, not at 10.

That number is the reorder point: the on-hand quantity that should trigger a purchase order. The formula is simple. Choosing the inputs is the real work.

This guide builds the number from Shopify's own inventory reports, shows why safety stock can dominate it, and separates the reorder point — when to buy — from the order quantity — how much to buy.

Who this is for: small Shopify stores that hold physical stock and replenish it from suppliers. What it is not: a demand forecast for launches, viral products or perishable goods. A straight-line average cannot see an influencer post, a holiday or a supplier shutdown unless you put that risk into the inputs.

The formulaDemand during lead time, plus a buffer

Shopify gives the standard formula as:

The first part is lead-time demand: what you expect to sell while the replacement is being made, packed and shipped. Safety stock is the cushion for a busier day or a slower supplier.

Shopify's reorder-point guide uses the same daily-sales × lead-time structure. Its safety-stock guide adds the maximum-demand/maximum-lead-time formula above. These are planning heuristics, not guarantees; a single freak day can make “maximum” far too expensive.

Worked exampleWhy six a day becomes a 210-unit trigger

Consider an unbranded skincare accessory sold by a Shopify store:

• Average sales: 6 units a day
• Average supplier lead time: 14 days
• Highest observed sales: 10 units a day
• Longest observed lead time: 21 days
• Landed cost: $18
• Selling price: $42 before fees

The normal lead-time demand is 6 × 14 = 84 units. The simple safety-stock formula is (10 × 21) − (6 × 14) = 126 units. The reorder point is therefore 210 units.

That buffer ties up 126 × $18 = $2,268 of cash. If the disruption arrives and all 126 units sell at a $24 price-minus-product-cost contribution, they protect $3,024 before platform fees, fulfillment, returns and ads. If the disruption never arrives, the same units occupy cash and shelf space.

That is the trade: safety stock buys availability with working capital. It is not free profit and it is not automatically waste.

Four productsOne percentage does not fit the catalog

Apply the same formula to four fictional SKUs:

The maximum formula is conservative for the slow import: one two-unit day combined with one 40-day shipment produces 59 units of safety stock against normal demand of 21. If those extremes happened in different years, 80 may be an expensive fiction. Use a representative high, not the largest cell a spreadsheet can find.

The Shopify inputsWhat to take from the reports

Shopify's current Inventory reports expose several useful pieces:

• Quantity sold per day is quantity sold divided by days in the selected period.
• Days of inventory remaining is ending inventory divided by average units sold per day; Shopify says that report uses the last 28 days.
• On hand includes Available, Committed and Unavailable stock, and excludes Incoming transfers.
• From October 1, 2026, Shopify's historical inventory reports measure On hand rather than Available quantity.

That last change matters. A reorder point compares with physical stock that still belongs to you, but some on-hand units cannot satisfy a new online order: they may be committed, damaged or held as safety stock. If your decision is “can the next customer buy it?”, look at Available. If the decision is “how much inventory do I own and what should I order?”, reconcile On hand, committed units and incoming stock rather than reading one number in isolation.

Shopify also warns that deleted variants do not preserve all future historical reporting, depending on deletion date. Archive or document a discontinued SKU before deleting data you still need for seasonality.

The window28 days can be right and still mislead

A 28-day average reacts quickly. That is useful for a growing bestseller and dangerous just after a promotion.

Suppose the worked SKU usually sells four a day, then sells 12 a day for one promotion week. Its 28-day average becomes six. If the promotion will not repeat, using six orders 50% too early. If the promotion starts a lasting new baseline, the older four is the misleading number.

Use three views:

1. 01Recent velocity: last 28 days, matching Shopify's days-remaining logic.
2. 02Normal velocity: a longer period with one-off campaigns labelled.
3. 03Known forward demand: an upcoming sale, wholesale order or seasonal peak.

Choose the rate that describes the lead-time window ahead, not the prettiest historical average. Before a promotion, the unit economics need checking too: Black Friday discount break-even shows why more orders can still create less profit.

Lead timeMeasure the whole wait

Lead time begins when you place the order and ends when saleable units are available. It includes:

• supplier production or picking
• consolidation and export paperwork
• freight
• customs
• receiving and quality checks
• time before your next scheduled order, if you buy only weekly

Do not use the carrier's “five-day shipping” promise for a supplier that takes nine days to manufacture. Record promised and actual arrival dates for several orders. Use the average for the base formula and a realistic late case for safety stock.

The IEEPA tariff refund guide shows another reason landed inventory needs history: duty can sit in the cost of units still on the shelf even after a cash refund arrives. Freight and duty also belong in landed unit cost, not only in a P&L expense bucket.

Reorder point is not order quantity

The reorder point answers when. Order quantity answers how much.

If the worked SKU reaches 210 and the supplier sells cartons of 60, ordering the mathematical gap to 210 makes no sense: by the time you place the order, 210 is the starting stock, not the target after delivery. Decide the order size from:

• supplier minimums and carton sizes
• the number of days until the next planned order
• storage and cash limits
• expected demand until the order after this one
• incoming purchase orders already placed

The Inventory Tracker treats these separately. A product stores a reorder point and an order size. When stock reaches the threshold it joins a purchase list grouped by supplier; the suggested quantity is at least the order size, and quantities already on an open order are subtracted so they are not bought twice. Inventory changes only when goods are actually received, because a purchase order is not stock on the shelf.

ABC prioritiesProtect the products that pay for the store

Shopify's ABC report grades variants by their share of revenue over the last 28 days: A products collectively make the first 80%, B the next 15%, C the last 5%. Revenue is not profit, but the split is useful for attention.

• Give an A product a better-measured lead time and a service-level buffer.
• Keep a C product lean unless it enables another sale.
• Review high-margin products separately; a lower-volume item can matter more than a revenue grade suggests.

The Inventory Tracker applies the same 80/15/5 revenue split and also ranks by profit, using the weighted-average landed cost of the units sold. The Business P&L then answers the company-wide question: whether margin from keeping those shelves full covers ads, software, rent and payroll.

Where these numbers come from

• Formula: Shopify's reorder-point and safety-stock guides. The maximum-case buffer is a simple operational heuristic, not a statistical service-level model.
• Shopify fields: Shopify Help Center Inventory reports, checked October 19, 2026. Shopify's interface and plan availability can change; the arithmetic does not depend on a menu label.
• Worked SKU: average 6/day, maximum 10/day, average lead 14 days, maximum 21 days, $18 landed cost and $42 price. All are assumptions, not merchant data.
• Cash tradeoff: 126 buffer units × $18 = $2,268 tied in stock; $42 − $18 = $24 contribution before every non-product cost, so 126 sold units protect at most $3,024 at that layer.
• Bias: pairing maximum demand with maximum lead time assumes they can happen together. That deliberately overstates stock needed when the events are independent. A 28-day average can either overstate demand after a one-off campaign or understate it before a seasonal peak.

FAQShopify reorder points

What is the reorder point formula?
Average daily sales multiplied by supplier lead time, plus safety stock. If a product sells six a day, takes 14 days to arrive and needs a 126-unit buffer, its reorder point is 210.

Does Shopify calculate reorder points automatically?
Shopify documents automatic reorder-point calculations in its low-stock tooling based on lead time and daily sales, but availability and interfaces vary. You can calculate the same threshold from inventory reports and store it in any inventory system.

Should I use Available or On hand inventory?
Available answers what can be sold now. On hand also includes committed and unavailable units, but excludes incoming transfers in Shopify's month-end report. For purchasing, reconcile all three plus open orders; do not compare a reorder point blindly with one headline number.

How much safety stock should a small store hold?
Enough to cover a realistic demand or supplier delay, not necessarily the worst day ever recorded. Start with the maximum-demand/maximum-lead-time formula, then reduce outliers that cannot reasonably coincide and raise the buffer before known peaks.

How often should reorder points change?
Review them when sales velocity, supplier lead time, seasonality, price or order cadence changes. For fast movers, monthly is a reasonable starting rhythm; before a major promotion, recalculate ahead of the event.

The practical answer

For every important SKU, write down average daily sales, the full supplier lead time and one honest late/high-demand case. Multiply first, add the buffer, and set that result as the trigger — not the quantity to purchase. The worked Shopify product does not become “low” at ten units. At its observed pace and supplier risk, 210 is the point where waiting becomes the expensive choice.