When a product sells out, most Shopify themes show a grayed-out "Sold out" button and nothing else. The shopper leaves, maybe to buy the same thing somewhere else, and you never find out how many sales you lost or how many people wanted that product.
Back in stock notifications fix both problems. Shoppers leave their email, you tell them the moment the product returns, and you get a waitlist that shows real demand. This guide covers the details that decide whether those alerts turn into orders: where the button goes, what the form asks, what the email says and when it's sent.
Why back in stock alerts matter
- They keep the sale alive. A shopper who signs up has told you they want this product. The alert brings them back when they can buy it.
- They show you real demand. A waitlist tells you which products, sizes and colors to reorder, and how many.
- They work on their own. Once they're set up, alerts go out automatically every time stock returns.
- They grow your email list. With the shopper's consent, every signup can join your marketing list too.
Keep sold-out products on your store
Before anything else: don't hide or delete products just because they're out of stock. A deleted product page returns a 404 error, loses the search rankings it has earned and gives shoppers nothing to sign up for. Keep the page live, show that the product is sold out, and offer the Notify me button instead.
If a product is gone for good, redirect its URL to the closest product or collection instead.
Where to place the Notify me button
On the product page, for each variant
The button belongs where the add-to-cart button would be. It should appear for the exact variant that's sold out, so a shopper who picks size M sees "Notify me" for M, even if size L is still available.
On collection pages
Shoppers may spot a sold-out product in a collection grid and never open it. A Notify me button on the product card catches them there too.
Clear and easy to tap on a phone
Many shoppers will see the button on a phone. Make it full width or close to it, give it a clear label such as "Notify me when it's back", and keep it visually different from a normal add-to-cart button.
What to ask for in the signup form
Keep the form short. It only needs:
- The shopper's email address.
- The variant they want, already filled in from the product page.
- An optional, unchecked checkbox if you also want to add them to your newsletter.
Then confirm the signup straight away, with a short message on the page and a confirmation email. Say what happens next: "We'll email you once when this is back in stock."
Tip: ask for consent separately. A restock alert is a message the shopper asked for. Adding them to your marketing list is a separate decision, so ask with its own checkbox and respect their answer.
What to write in the back in stock email
A restock email has one job: get the shopper back to the product while it's available.
- Put the product in the subject line. "Good news: the Linen Overshirt in M is back" beats "An update from our store".
- Show the product, variant and price with a clear image, so the shopper knows exactly what's back.
- Use one button that links straight to the product page with the variant selected.
- Be honest about stock. If only a few are available, say so. It's useful information, not a trick.
- Send it from your store's name and domain, so it's recognized and less likely to land in spam.
When to send restock alerts
Send them as soon as the stock is actually available to buy online, not when it arrives in a back room. Alerts that go out automatically when inventory is updated are the easiest way to get the timing right.
Two situations need more care:
- Small restocks and long waitlists. If 20 units come back and 300 people are waiting, most of them will find the product sold out again. Send the alerts in batches, starting with the earliest signups, and send the next batch when you restock.
- More than one location. If you keep stock in several places, make sure alerts only go out when the product is available where online orders are shipped from.
Back In Stock! Alert Engine, our restock alert app, sends alerts automatically when stock returns, and you can also send them manually or in batches.
Add low-stock and price-drop alerts
Restock alerts are the start. Two other alerts bring shoppers back at a useful moment:
- Low-stock alerts tell shoppers who are watching a product that only a few are left.
- Price-drop alerts reach price-sensitive shoppers when a product they wanted goes on sale, which is especially useful around Black Friday.
In Back In Stock! Alert Engine, low-stock alerts start on the Advanced plan and price-drop alerts are on Premium. If shoppers also save products to a wishlist, wishlist alerts can do the same for products they haven't bought yet.
Use your waitlist to reorder
Your waitlist is a list of customers who asked to buy something you couldn't sell them. Use it when you plan stock:
- Reorder the products and variants with the longest waitlists first.
- Check which sizes and colors sell out repeatedly, and order more of them next season.
- Look at email logs for opens and deliveries, to see whether your alerts are reaching people.
- Before a big sale, review what's on the waitlist and restock it in time. Our BFCM checklist covers this in more detail.
Connect alerts to your email marketing
If you use Klaviyo or Omnisend, send your alert subscribers there, with their consent, so a restock signup also grows your list. Back In Stock! Alert Engine syncs subscribers to Klaviyo and Omnisend on its Premium plan.
We built the app for merchants who were losing sales to stockouts. You can read how it works, and what merchants in the UK, UAE and India say about it, in the Back In Stock! Alert Engine case study.
Frequently asked questions
Do I need an app for back in stock alerts on Shopify?
Usually, yes. An app adds the Notify me button, stores each signup against the right variant and sends the email automatically when inventory returns.
Should I hide sold-out products?
Usually not. A hidden or deleted product page loses its search rankings and gives shoppers nothing to sign up for. Keep it live with a Notify me button, and redirect the URL only if the product is gone for good.
Should I send the alert to everyone on the waitlist at once?
Only if you have enough stock for them. If the restock is small compared with the waitlist, send the alerts in batches, starting with the earliest signups.
Can I show the Notify me button on collection pages?
Yes, with an app that supports it. In Back In Stock! Alert Engine, the Notify me button on collection pages is part of the Premium plan.