Back in stock flow teardown.

A back in stock flow tells a shopper the moment a product they wanted is available again. It triggers on a Subscribed to Back in Stock event, sends one fast alert when inventory returns, and optionally a second nudge if stock is limited. Speed and accurate inventory data matter far more than design.

Trigger and filters.

Subscribed to Back in Stock metric, created when a shopper signs up on a sold out product page. The send is released by the inventory update.

• Flow filter: has not purchased the product since subscribing
• Trigger filter: variant, not just product, matches the one requested
• Flow filter: inventory is above a minimum threshold when sending
• Smart sending off, because this message is one the shopper explicitly asked for

Sequence and timing.

1. 1. Confirmation of the alert (Immediately after signup)

   Acknowledge the request, so the shopper knows they are on the list.

2. 2. Back in stock alert (As soon as inventory returns)

   Deliver the single message they asked for with a direct link.

3. 3. Limited stock nudge (1 day later)

   If still unpurchased and stock is low, say so honestly.

4. 4. Alternative suggestion (3 days later)

   If the item sold out again or was not bought, suggest a close substitute.

Branch logic.

• Conditional split on stock level, sending the nudge only when inventory is genuinely low
• Split on whether the profile is a marketing subscriber, offering a signup in the alert if not
• Split on variant availability, suggesting another size or colour when the chosen one is gone again

Copy outline.

• Confirmation

  Short, plain note with the product image and how you will notify them.

• Alert

  Lead with the product name and the word available, one button to the exact variant.

• Nudge

  Honest note that stock is limited, plus similar items if it sells out.

What to watch.

• Click through rate on the alert, normally the highest in your account
• Time between restock and send, which should be short
• Number of subscribers per product, which guides what to reorder from suppliers
• Orders from the alert versus the nudge

Common mistakes.

• Sending alerts before stock is actually available to buy
• Treating the opt in as general marketing consent
• Not matching the variant, so shoppers click through to a sold out size
• Leaving the flow live for discontinued items

This is a starting structure, not a promise of results. Timing and offers depend on your product, your repurchase window and your list, so test and adjust.

Want this built and tested for you? See our klaviyo email marketing service or book a free audit.