How to Automate Low-Stock and Reorder Alerts for a Retail Shop or Small Wholesaler

Running out of the thing everybody wants is a quiet kind of expensive. Nobody complains. They buy it somewhere else, and the shelf tells you nothing until a Saturday when it is empty and the supplier takes two weeks.

The opposite failure is just as common and easier to see: money sitting in three cases of something that sells twice a month, bought because a reorder happened out of habit.

This guide builds a low-stock and reorder alert that reads the stock figures you already have, tells you what to order and from whom, and drafts the supplier email. Setup takes about three hours.

What you are building

A scheduled automation that pulls stock levels and recent sales out of your point of sale or inventory system, compares each product against a reorder point you set once, and sends you a single ordered list twice a week. Each line says what to order and from whom. The supplier emails arrive as drafts for you to check.

Tools: your point of sale or inventory software, a Google Sheet, an automation tool such as Zapier, Make or n8n, an AI assistant such as ChatGPT or Claude, and the email account you place orders from.

Step 1: set a reorder point for every line that matters

An alert that fires on a fixed number for every product is noise. The point at which you need to reorder depends on how fast a line sells and how long that supplier actually takes.

The rule is simple arithmetic and it belongs in the spreadsheet rather than in the model. Take average units sold per week, multiply by the number of weeks the supplier takes to deliver, then add a buffer of one week of sales. That is your reorder point. Anything at or below it goes on the list.

• ·Product name, and the code your supplier uses as well as your own.
• ·Supplier, plus the minimum order quantity or value if they have one.
• ·Lead time in weeks, as the supplier actually performs rather than as the price list claims.
• ·Average units sold per week, recalculated monthly from your own sales export.
• ·The reorder point and the order quantity, both as formulas in the sheet.
• ·A flag for seasonal lines, so the alert can be told to ignore them out of season.

Start with your top fifty lines by revenue. A shop with two thousand codes does not need a reorder point on all of them, and trying to set one for every code is how this build gets abandoned on day two.

Step 2: get the figures out automatically

1. 1Set your point of sale or inventory system to export stock on hand and units sold on a schedule, or connect it to your automation tool if a connector exists.
2. 2Catch the export in the automation tool and write it into the sheet, replacing the previous figures on a data tab.
3. 3Keep your reorder settings on a separate tab, so an import can never overwrite the work you did in step one.
4. 4Use formulas to join the two tabs by product code and calculate the gap between stock on hand and the reorder point.
5. 5Sort by that gap. The worst line sits at the top, which is the only sort order that matters at seven in the morning.

If your system cannot export anything useful, count the top fifty by hand on a fixed day each week and type the numbers in. It takes about fifteen minutes, every other part of this still runs on its own, and after a month you will know whether the report is worth changing your till over.

Step 3: the alert

Twice a week suits most shops. Often enough to catch a fast mover, rare enough that you still read it.

Grouping by supplier is the detail that makes the alert usable. You do not order product by product, you place one order per supplier, and a list in that shape turns into placed orders in ten minutes.

Step 4: draft the purchase orders

The last step of the alert is one draft email per supplier, sitting in your outbox waiting for you to check the quantities.

The instruction not to state prices is deliberate. A price quoted back to a supplier from stale data is an argument you will have at the point of invoice, and it is the sort of error that is easy to prevent and tedious to unpick.

Check the quantities against what you know before sending. A line that emptied because of one unusual bulk order will otherwise reorder itself into a problem.

Step 5: review the settings once a month

A reorder point set in March and never touched again is wrong by June. Once a month, recalculate average weekly sales from your own export, update the lead times where a supplier has been consistently slower than promised, and switch the seasonal flags on and off.

Add two lines to the sheet while you are in there: anything you ran out of since last month, and anything you now have too much of. Six months of those two columns will tell you more about your buying than any report you could subscribe to.

What changes

The shelf stops being the thing that tells you. Ordering becomes two short sessions a week against a list that is already sorted and already grouped, and the only decision you are making is whether the quantity looks right.

Stock alerts and the weekly rhythm around them belong to Workflow 07: Run a Leaner Business, the AutomateFirst module about the operating rhythm and the small systems that keep everything else running. This guide is one complete build from it, free. The playbook has seven workflows for one payment of $297, with a 30 day refund.