How to announce a restock
Announce a Shopify restock in the right order: the waitlist first through a Klaviyo back in stock flow, then past buyers, then the list, sized to the stock.
What this is for
A restock is one of the few emails people have asked you to send. The mistake is treating it like any other announcement: one campaign to the whole list, sent whenever the boxes are unpacked. The people who asked to be told get the news at the same moment as everyone else, the stock is gone in an hour, and most of the list clicks through to a sold-out page.
This guide sets up the order that avoids that: a sign-up on sold-out pages, a back in stock flow in Klaviyo that tells waiting shoppers first, then a wider announcement sized to how much stock is left. What the alert email should say is on the back in stock flow page; this guide is the plan and the setup.
Time needed and what you need
Time needed: about 90 minutes. Forty-five minutes for the form and flow the first time, then half an hour per restock to size the notifications and write the wider announcement.
- Klaviyo connected to your Shopify store
- Products set to stop selling when stock hits zero, so sold-out pages show as sold out
- The restock quantity per variant and the date it will be sellable
- A segment of past buyers of the product, if you plan to tell them second
The steps
Set up steps 1 to 3 once. Steps 4 to 7 are what you do each time stock comes back.
1. Put a notify-me sign-up on sold-out product pages
Publish a back in stock form in Klaviyo's form editor. On a Shopify store it adds a button to any product page that is out of stock and removes it again when stock returns, so you do not have to edit pages by hand each time something sells out. source, checked 28 September 2026
Leave sold-out products visible in your store rather than hiding them. A hidden product cannot collect sign-ups, and the list of people waiting is the most useful number you will have when you reorder.
2. Build the back in stock flow
Create the flow from Klaviyo's library, or from scratch on the Subscribed to Back in Stock trigger followed by the back in stock delay and one email. Turn Smart Sending off on that email: these people asked for the alert and should not be skipped because they had a newsletter the same day. source, checked 28 September 2026
3. Set the flow live before the product sells out
People only join the waiting queue if the email after the delay is Live or Manual. If you build the flow and leave it in Draft, sign-ups are recorded but nobody waits in the flow, and the restock reaches no one. Set it live as soon as the form is published. source, checked 28 September 2026
4. Size the notifications to the stock that is arriving
By default every waiting shopper is emailed the moment an item is back. That is right when you restock hundreds of units. For a small restock, set a restock minimum so a stray return does not set off the alert, and send in batches: a number of shoppers per unit restocked, with a wait between batches. source, checked 28 September 2026
Klaviyo's own example: 20 units back with 5 shoppers per unit means the 100 people who have waited longest hear first. The next batch waits for the interval you set and is sized to whatever stock is left. These settings apply to every back in stock flow in the account, and the settings tab only appears after the first sign-up has been recorded. source, checked 28 September 2026
5. Write the alert so it can be acted on in one tap
Name the exact product and variant in the subject line, show it, and link straight to its product page. Say plainly if stock is limited, but only give a number if it is true at the moment of sending. One email is enough for most restocks; Klaviyo advises keeping the flow to three messages at most. source, checked 28 September 2026
6. Tell past buyers and the list, only if stock allows
Once the waiting shoppers have had their batch and a few hours to buy, check what is left. If there is plenty, send a campaign: past buyers of the product first if it is something people reorder (the guide to segmenting by purchase behaviour builds that audience), then the wider list the next day. Exclude anyone who has already bought the restocked item. If only a handful remain, skip the wide announcement and let the flow keep working through the queue.
7. Watch for a second sell-out and learn from the queue
Klaviyo cannot recheck stock between an alert and any follow-up message, so if the product sells out again, pause follow-ups yourself. Afterwards, look at the back in stock report and the queue of people still waiting. The size of that queue per variant is your best guide to the next order quantity. source, checked 28 September 2026
A worked example
For a pet supplies store restocking its medium dog harness
Worked example (an invented store, with invented numbers)
While the medium harness was sold out, 340 shoppers signed up to be told. The store receives 60 units, sets a restock minimum of 10 and chooses 3 shoppers per unit with 12 hours between batches.
The first batch goes to the 180 people who waited longest (60 units times 3). They buy 44 harnesses, leaving 16. Twelve hours later the second batch goes to 48 more people (16 times 3), who buy 9, leaving 7. That is below the minimum of 10, so the flow stops notifying.
228 people were told and 53 harnesses sold in a day. The store skips the announcement to the full list, because 7 units cannot serve it, and orders 150 for the next restock with 112 shoppers still in the queue.
Common mistakes
Announcing to the whole list at the same time as the waitlist. The people who asked first lose out to people who did not ask at all, and they remember it. Give the waitlist a head start.
Leaving the back in stock flow in Draft. Sign-ups pile up with nowhere to wait, and the restock goes unannounced. Check the flow's status whenever you publish or edit the form.
Emailing hundreds of waiting shoppers about a restock of a dozen units. Most arrive to a sold-out page again. Use a restock minimum and batches for small restocks.
Selling the same stock in store and online without thinking it through. If you use Shopify POS, the flow counts shop-floor stock as available too, so an alert can go out for units that are sitting on a shelf across town. source, checked 28 September 2026
Doing this with Tilly
Once the waitlist has had its turn, Tilly's email marketing agent can write the wider restock campaign for 10 credits. It goes into Klaviyo as a draft and nothing is sent until you approve it, so you still decide whether the remaining stock justifies a send to the full list.
Questions people ask
How do I tell people who signed up before I had a flow?
Adding past profiles to a back in stock flow usually does nothing, because the back in stock delay works differently from a time delay. Klaviyo's advice is to send those people a campaign instead. source, checked 28 September 2026
Should a restock email include a discount?
No. These shoppers already want the product at its price; that is why they signed up. Save discounts for products people are not asking for.
Can I use Klaviyo's back in stock form on any platform?
The form builder version works on Shopify and BigCommerce. Other platforms need the snippet method in Klaviyo's installation guide instead. source, checked 28 September 2026
See this on your own store
Paste your store URL. The first pass takes about a minute and needs no account. Save a card (nothing is charged) and Tilly reads the whole store and works out who buys from you.