← All guides · By Agents4Ecom · Published Oct 14, 2026

How to Set Up a Low-Stock Alert in Shopify (Free, With Shopify Flow)

To get a low-stock alert in Shopify, use the free Shopify Flow app: create a workflow with the "Product variant inventory quantity changed" trigger, add a condition that the new quantity is at or below your reorder point and the prior quantity was above it, then add "Send internal email" (and optionally "Add product tags"). It works on Shopify Basic, costs nothing, and takes about 15 minutes.

Finding out you're sold out from a customer email is the worst way to find out. This guide walks through the setup, how to pick a reorder point, how to test it in one minute, and the mistakes that cause duplicate or missing alerts.

What will you have at the end?

• One email per variant the moment it crosses your reorder point. Not one per sale, just one when it crosses.
• The product tagged low-stock, so you can filter Products in your admin and see everything that needs reordering.
• Optionally, a draft reorder note you can send your supplier.

Nothing customer-facing changes. The workflow never edits prices or inventory.

What do you need?

How do you pick a reorder point?

Your reorder point is the stock level at which you need to place an order so you don't run out before it arrives. A simple rule of thumb:

Reorder point = average units sold per day × supplier lead time in days, plus a small buffer.

Example: you sell about 2 units a day and your supplier takes 10 days. 2 × 10 = 20 units, plus a buffer of 5 gives a reorder point of 25.

If you don't know your daily sales, start with a round number (say 5 or 10) and adjust after a month. A single store-wide number is fine to begin with. You can split fast and slow sellers later.

How do you build the workflow?

1. In your admin, open Apps → Shopify Flow (install it from the App Store if needed) and click Create workflow.
2. Select the trigger Product variant inventory quantity changed. Shopify's docs list the data this trigger provides, including the product, the variant and inventoryQuantityPrior, the quantity before the change.
3. Add a Condition with two parts joined by AND:
4. the variant's inventory quantity is less than or equal to your reorder point, and
5. inventory quantity prior is greater than your reorder point.
6. On the True branch, add Add product tags with low-stock. Leave the False branch empty.
7. Add Send internal email. Put your address in the recipient field. In the subject and message, use Liquid variables for the product title, variant title, SKU and quantity. Paste the whole text in one go: the Flow editor auto-closes {{ as you type, which can garble variables.
8. Rename the workflow (for example "Low-stock reorder alert"), click Turn on workflow, then confirm with Turn on in the dialog.

The "prior quantity above the threshold" part is what most tutorials miss. Without it, every sale below the threshold fires another email. With it, you get exactly one alert when the variant crosses the line.

Shopify also has a template, "Send weekly email summary with list of low stock variants," if you'd rather get one weekly digest than instant alerts.

The finished version of this workflow, with copy-paste subject and message, a store profile worksheet and a supplier email prompt, is our Low-Stock Reorder Alert recipe. It passed a live test in a Shopify Basic development store on October 14, 2026. With the recipe you skip the build: download, import, add your email, turn on, in about 5 minutes. (Shopify signs Flow files, so you type your email once.)

How do you test it in one minute?

1. Pick a test product with tracked inventory above your reorder point, say 10 units with a reorder point of 5.
2. Change its quantity in one step to below the threshold (10 → 3) and click Save at the top of the product page. Inventory edits aren't applied until you save.
3. Within about a minute you should see the email arrive, the low-stock tag on the product, and a success under the workflow's Recent runs.
4. Set the quantity back and save. Done when you got exactly one email.

Why isn't my low-stock alert working?

• No email at all. Open Recent runs. If there's no run, the trigger didn't fire, usually because the product wasn't saved. If the run shows the condition as False, check the threshold numbers.
• Duplicate emails. The "prior quantity above threshold" condition is missing or inverted.
• Garbled {{ }} in the email. You typed the Liquid instead of pasting it. Delete the field and paste it in one go.
• Workflow never runs. It may not be turned on. After Turn on workflow, you must confirm Turn on in the dialog.
• Multiple locations. The trigger fires on inventory changes, and how quantities are counted across locations can differ from what you expect. Test with your real setup, and check the Shopify Help Center page for this trigger.

How can AI turn the alert into a supplier email?

Flow on Basic doesn't call an AI model, but you don't need it to. Keep a prompt like this saved:

You are my purchasing assistant. Here's a low-stock alert from my store: [paste email]. My supplier is [name], lead time [days], and I want enough stock for lead time plus 30 days of sales at [units/day]. Draft a short, friendly reorder email with the SKU and quantity.

Paste the alert into ChatGPT or Claude, check the numbers, and send. Later, if you move to Shopify Grow or use a tool like Make, that step can be automated.

What else should you automate after this?

Low stock is one job. Others that work on Basic with built-in Flow actions include a daily stuck-orders alert and a weekly KPI email. See what you can automate in a Shopify store for a fuller list.

FAQ

Will it alert me on every sale?

No, as long as you include the "prior quantity was above the reorder point" condition. Then you get one alert when a variant crosses the line.

Does it work on Shopify Basic?

Yes. Shopify Flow is free on Basic, Grow, Advanced and Plus, and this workflow only uses built-in actions.

Can it reorder from my supplier automatically?

Not in this setup, on purpose. The workflow tags the product and emails you. You stay in control of purchasing, and nothing writes to your inventory or prices.

Can I get one weekly summary instead?

Yes. Shopify's template library includes a weekly low-stock variants summary built on the Scheduled time trigger.

Does it work for products that don't track inventory?

Turn on inventory tracking for the variants you want alerts on. Untracked variants don't have meaningful stock counts to compare.

Next step

Run the free AI audit to see how many of your variants are already sold out and which other jobs are worth automating. It reads only public storefront data, with no login. Or skip ahead and get the Low-Stock Reorder Alert recipe.

Related guides

• What Is Shopify Flow (and Is It Free?)
• Shopify Flow Examples for Small Stores: 10 Workflows That Work on Basic
• AI Agents for Shopify: What They Are, What They Aren't, and the Easy First Step
• All automation recipes