How to Set Reorder Points for Your Shopify Store

A reorder point (ROP) is the inventory level at which you need to place a new purchase order to avoid running out of stock before your next shipment arrives. For Shopify stores, it's calculated as: (average daily sales × supplier lead time) + safety stock. Get this number right, and you stop stockouts before they happen.

Most Shopify merchants either set reorder points too conservatively (tying up cash in excess inventory) or too aggressively (constantly scrambling to restock). This guide walks through the math, the nuances, and how to actually implement reorder points in practice.

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What Is a Reorder Point and Why Does It Matter?

A reorder point is a trigger — not a "we're out of stock" alarm. It's the moment you should place an order, accounting for the fact that your supplier needs time to fulfill it and your store keeps selling in the meantime.

Without a defined reorder point, most merchants end up doing one of two things:

1. Eyeballing it — checking inventory when they remember to and placing orders based on gut feel
2. Over-ordering — keeping large safety buffers that inflate storage costs and tie up working capital

Neither works well at scale. A store moving 20 SKUs can get away with gut feel. A store with 200+ SKUs cannot.

The business case is concrete: a single stockout on a top-selling product doesn't just lose you that sale — it pushes customers to competitors, drops your conversion rate on that product page, and can tank your paid ad ROAS if you're driving traffic to an out-of-stock listing.

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The Reorder Point Formula

The standard reorder point formula is:

ROP = (Average Daily Sales × Lead Time in Days) + Safety Stock

Let's break down each component.

Average Daily Sales is the mean number of units you sell per day over a representative time period. Use 30–90 days of data for stable products. For seasonal products, use the equivalent season from the prior year.

Lead Time is the number of days between placing an order with your supplier and receiving it at your warehouse. Include processing time on the supplier's end — not just shipping transit time. If your supplier takes 3 days to pick and pack and 7 days to ship, your lead time is 10 days.

Safety Stock is a buffer for variability — unexpected demand spikes or supplier delays. We'll cover how to calculate this below.

Example Calculation

Say you sell a candle that moves an average of 8 units/day. Your supplier has a 14-day lead time. You hold 3 days of safety stock.

ROP = (8 × 14) + (8 × 3)
ROP = 112 + 24
ROP = 136 units

When your inventory hits 136 units, you place your next order. By the time it arrives (14 days later), you'll have sold roughly 112 units, leaving you with ~24 units as a buffer.

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How to Calculate Safety Stock

Safety stock is where most guides get hand-wavy. Here's a practical approach for Shopify merchants.

The simplest safety stock formula:

Safety Stock = (Max Daily Sales − Average Daily Sales) × Lead Time

If your candle sells a max of 12 units/day but averages 8, and lead time is 14 days:

Safety Stock = (12 − 8) × 14 = 56 units

That's a conservative buffer that handles a demand spike to your historical maximum. For most DTC brands, this works well.

A more nuanced approach uses a service level multiplier (Z-score) based on how often you want to avoid a stockout:

Service Level	Z-Score
90%	1.28
95%	1.65
99%	2.33

Safety Stock = Z × σ(demand) × √Lead Time

Where σ(demand) is the standard deviation of your daily sales. For a store doing 500 orders/month across 50 SKUs, this level of precision makes sense for your top-10 revenue-driving products. For everything else, the simpler formula is good enough.

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Shopify's Built-In Reorder Point Functionality (And Its Limits)

Shopify has some native inventory tooling, but it's limited.

Stocky (Shopify's free inventory app, available to some POS Pro users) does calculate reorder points based on lead time and average daily sales. If you have access to it, it's a decent starting point. The formula it uses is straightforward: lead time × average daily unit sales, without a formal safety stock calculation.

The core problem with relying on Shopify's native tools:

• No automatic alerts — Shopify can show you low stock warnings in the admin, but it won't proactively notify you when you hit a reorder point
• No sales velocity tracking — the admin doesn't surface daily sales rates or trend data per variant in an actionable way
• No forecasting — you can't see "at your current sell rate, this product runs out in 11 days"

For merchants with fewer than 20 SKUs, manually checking the Shopify admin might be fine. For anyone running a real catalog, you need something that monitors continuously and alerts you.

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How to Set Reorder Points in Practice

Here's a step-by-step process to actually implement this for your store.

Step 1: Pull Your Sales Velocity Data

Export your Shopify sales data for the past 60–90 days (or use an app that surfaces this automatically). Calculate average daily units sold per SKU. Flag high-variance SKUs — products that sell 2 units one week and 40 the next need wider safety stock buffers.

Step 2: Confirm Lead Times Per Supplier

Don't guess. Email each supplier and ask: "What's the typical time from when I submit a PO to when it ships?" Then add 2–3 days for your own processing time. Document this somewhere accessible — a simple spreadsheet works.

Step 3: Calculate ROP Per SKU

Apply the formula: (avg daily sales × lead time) + safety stock. For your top 20% of SKUs by revenue, use the variance-based safety stock formula. For the rest, use a flat 3–5 day buffer.

Step 4: Set Threshold Alerts

This is where most manual systems break down — you do the calculation once, set a number in a spreadsheet, and then forget to check it. What you actually need is a system that:

• Compares current inventory against your ROP continuously
• Alerts you the moment a product crosses that threshold
• Updates your reorder points as sales velocity changes

Tools like Alertr are built specifically for this: you configure reorder thresholds per SKU, and it alerts you via email or Slack when stock hits that level. It also tracks sell rates and shows days-of-stock estimates, so you can see why a product is approaching its reorder point — whether it's a demand spike or just steady depletion.

Step 5: Review and Adjust Quarterly

Reorder points aren't set-and-forget. Seasonality, supplier changes, and product lifecycle all affect the right numbers. Set a calendar reminder to review your top 50 SKUs every 90 days and adjust thresholds accordingly.

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Common Mistakes When Setting Reorder Points

Using the wrong time window for average sales. A 7-day average during a promotional period will massively overstate your typical velocity. Use a longer window and exclude obvious outliers like flash sales unless you run them regularly.

Ignoring lead time variability. If your supplier usually delivers in 10 days but sometimes takes 18, build that into your buffer. Use your supplier's maximum lead time for safety stock calculations, not the average.

Setting the same reorder point for all variants. A small and an XL of the same shirt might have wildly different sell rates. Reorder points should be per-variant, not per-product.

Never updating thresholds. A product that sold 5 units/day in Q3 might sell 20/day in Q4. If you set the ROP in September and don't revisit it, you'll stockout every holiday season.

Confusing reorder point with reorder quantity. The ROP tells you when to order. How much to order (EOQ — Economic Order Quantity) is a separate calculation. Don't conflate the two.

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Choosing the Right Tool

If you're managing more than 50 SKUs, you need software. Here's an honest comparison of the options:

• Alertr (getalertr.com): Built specifically for low stock alerts and reorder point monitoring. Free tier covers 50 SKUs. Pro is $29/mo (currently $19/mo locked in beta). Best fit for DTC brands with 100–2,000 SKUs who want clean alerting without enterprise complexity.

• Bee Low Stock Alert & Forecast: At $5.99/mo, it's a solid budget option with forecasting built in. Auto-calculates reorder quantities based on sales velocity. The main complaint is limited data export between stores — a real issue if you're multi-store.

• Stockie: $4.99/mo with 71 reviews at 5 stars. Good forecasting using sales history and automated reorder calculations. A legitimate option at that price point.

• Prediko: $49/mo and up, with AI-driven forecasting and purchase order management. Powerful, but reviewers note it has a learning curve. Better suited to operations teams than solo founders.

• Inventory Planner by Sage: Enterprise-grade with pricing to match ($4k/year reported by some users). If you're doing multi-million dollar revenue and need deep forecasting, it's worth evaluating. For most DTC brands, it's overkill.

The right tool depends on your SKU count, budget, and how complex your supplier relationships are. For most Shopify brands in the 100–1,000 SKU range, a focused alerting tool is more useful than a bloated inventory platform.

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Setting Reorder Points Is an Ongoing System, Not a One-Time Task

The math is simple. The discipline is harder. What separates stores that consistently stay in stock from those that perpetually scramble is having a system — calculated thresholds, continuous monitoring, and actual alerts that interrupt your workflow before a stockout happens.

Start with your top 10 revenue-driving SKUs. Calculate their reorder points using the formula above. Set up alerts so you're notified when they hit those levels. Then expand to your full catalog.

If you want a faster way to get there, Alertr has a free tier that covers up to 50 SKUs — enough to get your most important products under automated monitoring today. No complex setup, no enterprise contract. Just alerts when your inventory needs attention.

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