Replenishment Email Flow in Klaviyo:
Time Reorder Reminders to When Customers Run Out

A replenishment email flow reminds customers to reorder just before they run out. In Klaviyo, trigger it on Placed Order, filter by product, and set the delay from days of supply. Klaviyo's own rule: for a 30-day supply, send the first reminder about 25 days after purchase, then a second 3 days later.

For BFCM buyers, this flow does most of the January work on its own. Someone who bought a 30-day supply on Nov 27 runs out around Dec 27. Someone who bought a 60-day supply runs out in late January. The flow catches both without a campaign.

This post is part of our repeat purchase rate guide. It covers the math, the Klaviyo build, copy, and when a subscription beats a reminder.

How do you calculate days of supply for each product?

Days of supply is units in the pack divided by units used per day. Do it per SKU and pack size.

The "typical use" column is the label instruction, not real behavior. Check it against your own data. Export Shopify's Returning customers report, keep customers whose first 2 orders were the same SKU, and find the median days between them.

If the median is 38 days on a 30-day product, people stretch it. Move the first reminder to day 33. If it is 26 days, people overuse or share. Move it earlier.

Add shipping time. If orders take 5 days to arrive, the reminder must land at least 5 days before the customer runs out. Start the delay count from Placed Order, not delivery, unless you trigger on a fulfillment event.

How do you set up a replenishment flow in Klaviyo?

Klaviyo's help center documents the build in its replenishment flow guide. Here is the setup with the settings that matter:

1. Start from a template. Go to Flows, Create Flow, then Browse by goal, Encourage repeat purchases. Shopify stores get pre-built replenishment templates. Or click Build your own and set the trigger to Placed Order.
2. Add a trigger filter. Use Items contains with the product name, for example "Daily Supplement 60ct". One flow per product or per group of products with the same cycle.
3. Add the profile filter. Placed Order zero times since starting this flow. This stops reminders after a reorder.
4. Scope the stop condition to the product. A generic filter exits the customer if they buy anything, including an unrelated gift. Klaviyo suggests a conditional split checking they have not ordered that product since starting the flow.
5. Set delays. First email at days of supply minus 5. Second email 3 days later. Optional third after the supply runs out.
6. Review and turn on. Set each message to Live.

Klaviyo tracks 2 order events from Shopify. Per its Shopify data reference, Placed Order fires once per order and Ordered Product fires once per unit, with Quantity always 1. Placed Order's Item Count is line items, not units. So a customer who buys 2 bottles enters a Placed Order flow once, with a 30-day delay, though they have 60 days of product.

The cleanest fix is to sell multi-packs as their own product, such as "Daily Supplement 3-Pack", and give that product its own flow with a 90-day cycle.

What should the replenishment emails say?

Keep them short. The job is a one-click reorder. Klaviyo recommends a Buy Again button linking straight to the product and an optional block of related items.

A 3-email structure that works for most consumables:

Klaviyo's guide suggests 2 reminders and then 1 follow-up after the cycle ends, with an incentive on the follow-up. It also warns against sending too many. Three is the ceiling.

Subject line examples:

• Email 1: "About 5 days of serum left"
• Email 1: "Your coffee runs out next week"
• Email 2: "Reorder today, it arrives before you run out"
• Email 2: "Free shipping on your refill until Sunday"
• Email 3: "Still on your first bottle?"
• Email 3: "How is the supplement working for you?"

Use the product name and a number. Avoid "We miss you" in email 1. The customer has not left yet.

For SMS, send one message at the email 2 point to subscribers who consented to SMS marketing. Keep it under 160 characters with a direct product link. Our Klaviyo post-purchase flow post covers how this fits with the rest of the post-purchase sequence.

Should you use Klaviyo's predicted next order date?

Use it for one-time buyers when usage varies. Skip it for products with a clear cycle.

Klaviyo's predictive analytics give each eligible customer an expected date of next order. It uses the person's own order pattern, or all customers' behavior when that pattern is thin. Klaviyo says you can build segments from expected next order date and point campaigns and flows at them.

Know its limits before you rely on it:

• Eligibility. You need at least 500 customers with orders, 180 days of history, orders in the last 30 days, and some customers with 3+ orders.
• It ignores products. The prediction does not consider what was ordered. A store selling a 30-day serum and a 6-month cleanser gets one date for both.
• It repeats for loyal buyers. Klaviyo advises against counting down to it for repeat customers, because they would get the same sequence before every order and unsubscribes may rise.

Klaviyo's own advice: if most product categories have known cycles, use the standard replenishment flow. A Klaviyo community answer agrees that the prediction is most effective for new customers and for products with irregular usage.

A reasonable split: product-specific flows for your top 5 SKUs by reorder volume, plus one predictive segment for first-time buyers of everything else.

How does a replenishment flow perform?

Klaviyo does not publish benchmarks for replenishment flows specifically. Its 2026 benchmark report, covering 183,000+ accounts, gives flow-wide figures:

• Flows were about 5.3% of sends and nearly 41% of email revenue.
• Flow click rate averaged 5.58%, against 1.69% for campaigns.
• Health and beauty flows averaged a 1.65% order rate; food and beverage, 1.79%.

What drives your number: how accurate the delay is, whether the link goes straight to the product, and whether the product delivered on its first use. A reminder for a product the customer did not like will not convert at any timing.

Measure it per flow. Track placed order rate per email and the share of reorders using a code. If email 3 drives most revenue and it carries a discount, your first 2 emails are probably mistimed.

When do subscriptions beat replenishment reminders?

When the customer wants the same product on the same cycle every time. Subscriptions remove the reorder decision entirely.

Recharge's 2023 report on 15,000+ merchants found subscribers averaged 45% retention after 6 months and 33% after 12 months. The same report found 35% of subscribers adjusted an order in a year, through skips, frequency changes or swaps. Flexibility is part of why they stay.

Our view: do not push a subscription on the first reminder. A buyer who reorders once on their own has shown the product fits. Offer subscribe and save to that person.

Subscriptions bring their own work: failed payments, skip management and cancellation flows. Our subscription churn guide covers that side.

When is a replenishment flow not worth building?

It is not worth much for products bought once or rarely, such as mattresses, furniture, cookware and most electronics. Use a cross-sell or referral flow there.

It is also overkill to build 40 product-specific flows on a small list. If you have under 1,000 orders a month, build 1 to 3 flows covering your top SKUs and send everyone else a general post-purchase sequence. You can build this in-house in an afternoon from Klaviyo's template.

What should you do before January?

Build or audit the flow by mid-December, so BFCM buyers with 30-day products get their first reminder around Dec 22 to 27.

Pair it with the rest of the Q1 plan:

• Split gift buyers out first. A gift buyer did not use the product. Our gift buyer segmentation post covers how to tag them.
• Clean the list in January so reminders land in the inbox. See email list cleaning after Black Friday.
• Do not cancel out reminders with a January sale. A sitewide code on Jan 5 teaches buyers to ignore the reminder and wait.

For the cohort view, see how to retain Black Friday customers. If you want us to review your timing against your order data, book a call.