- A Klaviyo back in stock flow triggers on Subscribed to Back in Stock, then waits at a Back in stock delay until the item is restocked. No time delays needed.
- Klaviyo’s own setup: no trigger or profile filters, usually one message, and Smart Sending off so everyone gets the alert.
- The money is in two settings: the restock minimum and batch notifications, so 300 people don’t chase 10 units.
- On Shopify, publish Klaviyo’s back in stock form. It shows a “Notify me” button only on sold-out variants. Add SMS for anyone already subscribed.
- Price the lost demand with the abandoned cart calculator and fix the flow with the biggest leak first.
A Klaviyo back in stock flow is the easiest money in your account. The shopper found the product, wanted it, hit a sold-out page and still left you their email. All you have to do is tell them when it’s back.
Most stores set it up once from the template and never touch it again. That works, kind of. But the default sends one alert to everyone at the same moment, even when you restocked 12 units for 400 people. That’s where the tricks come in.
Here’s the exact build from Klaviyo’s own help article, the two settings that decide whether the flow sells or annoys, and copy you can steal.
Abandoned Cart Recovery CalculatorSold-out demand is lost demand. Plug in your numbers and see what recovering a slice of it is worth each month.Run my numbers →7 tricks for a Klaviyo back in stock flow that actually sells
1. Batch the alerts when stock is thin
By default, Klaviyo notifies every subscriber at once. If 300 people are waiting and you get 20 units back, 280 of them click through to a sold-out page again. Batch notifications fix this. Klaviyo’s example: 20 units restocked with “customers to notify” set to 5 means the oldest 100 subscribers get the alert first. The flow then waits before notifying the next batch, based on remaining stock.
2. Set a restock minimum
If you get 2 units back of a popular variant, don’t fire the alert. The restock minimum is the number of items that must be in stock before any notifications send. Set it high enough that the first batch can actually buy.
3. Turn Smart Sending off
Klaviyo says this outright for the back in stock message. Smart Sending skips people who got an email recently. These people asked for this alert. Let it through.
4. Write it like a personal heads-up
Short subject, the product name, one image, one button. “It’s back: [product]” beats a designed newsletter. Show the exact item they asked about, not your bestsellers.
5. Add urgency only if it’s true
If stock is limited, say so. If you batch the alerts, you can honestly say “you’re getting this first.” Don’t invent a countdown you don’t have.
6. Add SMS for people who are already subscribed
Klaviyo supports back in stock texts on Shopify and other platforms. Only current SMS subscribers receive them, and quiet hours can delay the text even after stock lands. So keep the email as the main alert and treat SMS as the fast lane.
7. Use the sign-up as a list-builder, carefully
Klaviyo’s form lets you add an optional checkbox for promotional marketing emails. Use it. A restock request is a high-intent sign-up, and the checkbox turns a one-time alert into a long-term subscriber. Find out what each one is worth with the email list value calculator.
How to set up the Klaviyo back in stock flow, step by step
Klaviyo has pre-built back in stock templates. Go to Flows, click Create flow, search “back in stock” and pick a template. Or build your own:
- Trigger: choose Your metrics, then Klaviyo, then Subscribed to Back in Stock. Klaviyo says not to add trigger or profile filters.
- Back in stock delay: drag it in directly after the trigger. Everyone waits here until their item is restocked.
- Message: add one email (or SMS) after the delay. No time delays needed, because the back in stock delay does the waiting.
- Smart Sending: off for this message.
- Content: make the email show the restocked product. Klaviyo recommends reviewing any template and matching it to your brand.
- Go live: use Review and turn on and set the messages to Live. Messages left in draft won’t send.
- Form: publish the back in stock form on your store, covered below.
One limit worth knowing: custom metrics can’t trigger this flow. Only Klaviyo’s own metric from a supported integration, a custom catalog, or the back in stock subscription API can.
The 2 settings most stores never change
You’ll find them in Settings > Other > Back in stock settings, or by clicking the Back in stock delay in the flow builder and choosing Edit. They are account-level, so one change applies to every back in stock flow you run. The tab only appears after at least one Subscribed to Back in Stock event is recorded, so submit a test sign-up first.
| Setting | What it does | My starting point |
|---|---|---|
| Restock minimum | Items that must be in stock before any alert sends | Low-stock brands: about the size of your usual first-day sales for that item. Big restocks: leave low. |
| Subscribers to notify per restocked item | How many people get the alert for each unit back in stock | Start with a small multiple, like 3 to 5 people per unit, then adjust based on how fast each batch buys |
| Wait between batches | Hours or days before the next batch, based on remaining stock | Long enough for the first batch to act. A few hours for fast sellers, a day for slower ones |
The “starting point” column is my rule of thumb, not Klaviyo guidance. Batches keep sending until stock falls below your restock minimum. If more units arrive mid-wait, Klaviyo recounts at the end of the wait period.
Also note: if you use Shopify POS plus an online store, Klaviyo counts inventory in your physical store as well as your warehouse. A “restock” can be a shelf in a shop, not stock you can ship.
Set up the back in stock form on Shopify
Klaviyo’s back in stock form works for Shopify and BigCommerce. Klaviyo.js (onsite tracking) must be on your storefront. Once published, Klaviyo automatically shows a customisable “Notify me” button on product pages when the selected variant is sold out, and hides it again when stock returns.
- Email field: for the restock alert, plus that optional marketing checkbox.
- Phone field: for text or WhatsApp alerts. Klaviyo requires explicit consent and disclosure language here, and the consent can’t be optional.
- Targeting: choose which products show the button. Skip discontinued items so you’re not collecting promises you can’t keep.
Klaviyo also notes that A/B testing isn’t supported on back in stock forms, so test the email instead.
Copy that works: one email, one follow-up
Email 1 (sends at restock)
Subject: It’s back: [product name]
Preview: You asked us to tell you first.
- Line 1: “Good news. The [product] you asked about is back in stock.”
- Product image, name, variant and price, pulled dynamically from the restocked item.
- One button: “Grab yours.”
- If stock is genuinely limited: “We restocked a small batch and we’re telling the waitlist first.”
Optional follow-up (1–2 days later)
Subject: Still want the [product]?
Filter it to people who haven’t placed an order since starting the flow. Add one review or a short “why people love it” line. No discount needed. They already wanted it.
Klaviyo’s guidance is to keep flows to 1–3 messages. For restock alerts, one plus an optional nudge is plenty.
What a back in stock flow can be worth
A Shopify store sells out of its bestselling hoodie in one colour. Over three weeks, 400 people sign up for the restock alert. The store gets 60 units back. Average order value is $70.
- Default (notify everyone): all 400 get the alert at once. Suppose the 60 units sell out in hours. 340 people click through to a sold-out page again. Some of them are annoyed. The flow made $4,200 in revenue, but it burned goodwill with most of the waitlist.
- Batched (restock minimum 10, 3 people per unit, 12-hour wait): the first batch is the oldest 180 subscribers. Suppose they buy 45 units. After 12 hours, Klaviyo recounts the 15 left and notifies the next 45. Same 60 units sold, same $4,200, but far fewer people hit a dead end.
- The bonus: if a quarter of the 400 ticked the marketing checkbox, that’s 100 new subscribers who joined while wanting something.
Run your own version: start with lost demand in the abandoned cart calculator, then check your order value in the AOV calculator.
Klaviyo back in stock flow not sending? Check these
From Klaviyo’s help docs and community answers:
- The message was in draft or manual. Messages must be Live before the test subscription, then switch the product from out of stock to in stock.
- Filters are blocking people. Remove trigger and profile filters on the trigger.
- Stock is below your restock minimum. Nothing sends until inventory reaches it.
- Smart Sending is on. People who got another email recently get skipped.
- The profile is suppressed. Check Recipient Activity for skipped or suppressed profiles. A pile of bounces? My guide to hard bounce vs soft bounce in Klaviyo explains what gets suppressed.
- Wrong inventory source. On Shopify with POS, shop-floor stock counts too.
To see what’s queued, click the Back in stock delay and open View back in stock reports. You can export activity to CSV, and also export everyone currently waiting.
Where the back in stock flow fits in your flows
It’s one of a family of intent flows. Each catches a different kind of “almost bought”:
- Browsed, didn’t add to cart: Klaviyo browse abandonment flow.
- Added to cart, didn’t check out: Klaviyo abandoned cart flow.
- Wanted it, but it was sold out: this flow.
- Bought it, need it again: a replenishment flow timed to the reorder window.
After the restock order, the customer moves into your post-purchase flows, which is where a one-time buyer becomes a repeat one. Track that with the repeat purchase rate calculator.
Quick checklist
- Trigger is Subscribed to Back in Stock, with no filters.
- Back in stock delay sits right after the trigger.
- One email, Smart Sending off, set to Live.
- Restock minimum and batch settings match how much stock you actually get.
- Form is published, with the marketing checkbox and SMS consent where it applies.
- You test it with a real sign-up and a real restock before you trust it.
Want Inboxoo to set this up for you?
We build and run Klaviyo email & SMS retention for Shopify brands and get paid on results.
Chat on WhatsAppWant to know the exact quotation? Contact now
FAQ
How does a Klaviyo back in stock flow work?
A shopper clicks “Notify me” on a sold-out product and fills out the form. Klaviyo records a Subscribed to Back in Stock event on their profile, which triggers the flow. The shopper then waits at the Back in stock delay until the item is restocked and meets your inventory and notification settings, and then the alert sends.
Should Smart Sending be on for back in stock emails?
No. Klaviyo’s help article says to turn Smart Sending off for the back in stock message so everyone who asked for the alert receives it. Smart Sending can skip people who got another email recently, which defeats the point of a requested alert.
How many emails should a back in stock flow have?
Klaviyo says you typically only need a single message. Its general flow advice is to keep flows between 1 and 3 messages. A sensible extension is one short follow-up a day or two later, filtered to people who haven’t ordered since starting the flow.
Why is my Klaviyo back in stock flow not sending?
Common causes from Klaviyo’s community: the flow messages weren’t set to Live before the test subscription, trigger or profile filters are excluding people, or inventory hasn’t reached your restock minimum. Also check Recipient Activity for skipped or suppressed profiles.
Can I send back in stock alerts by SMS in Klaviyo?
Yes, on supported setups such as Shopify, BigCommerce, PrestaShop and Magento 2. The person must be a current SMS subscriber, and quiet hours can delay the text even after the product is restocked.
Where are Klaviyo back in stock settings?
In Settings, then Other, then Back in stock settings, or by clicking the Back in stock delay in the flow builder and choosing Edit. The settings tab only appears after at least one Subscribed to Back in Stock event is recorded, and the settings apply to every back in stock flow in the account.
Want Inboxoo to set this up for you?
We build and run Klaviyo email & SMS retention for Shopify brands and get paid on results.
Chat on WhatsAppWant to know the exact quotation? Contact now
Keep reading
The Klaviyo browse abandonment flow
Trigger, filters, timing and a 2-email structure for the flow that catches window shoppers before they buy elsewhere.
8 min read →Klaviyo flowsThe Klaviyo abandoned cart flow setup
Trigger, filters, timing and discount rules for a cart flow that recovers revenue without training buyers to wait for a code.
7 min read →Klaviyo flows7 Klaviyo post-purchase flow examples
Seven copy-ready post-purchase builds with triggers, splits and timing, from thank-you to replenishment and VIP.
8 min read →- Klaviyo Help Center: How to build a back in stock flow
- Klaviyo Help Center: How to set up a back in stock form
- Klaviyo Help Center: How to use SMS in your back in stock flows
- Klaviyo Community: Back in stock flow not sending emails
Worked examples in this post use illustrative numbers, not client results. Benchmarks are linked to their original publisher.