What is attach rate, and which stores are missing the add-on?
The short answer
Divide transactions that include both a main product and its add-on by all transactions that include the main product, and you have the attach rate. Calculate it per store and per add-on, then compare stores with similar traffic and mix. A store running well below the network rate is missing add-on sales at the counter.
The attach rate formula, store by store
Why it matters
Add-ons often carry higher margin than the main product and cost nothing extra to acquire, because the customer is already buying. A low attach rate in a few stores leaves margin dollars behind on every main-product sale they make.
The question to ask
Copy this into Lexi as written.
How to work it out
1. Pair main products with add-ons. List each main product and the add-ons that belong with it, such as a helmet and lock with a bike.
2. Calculate attach rate by store. For each store, divide transactions containing the main product and the add-on by transactions containing the main product, for one quarter.
3. Follow up the customers who missed it. Find customers who bought the main product without the add-on in the last 60 days, and reach them by email or on their next store visit.
What the answer looks like
Illustrative output on sample data
Illustrative example: how Lexi answers this for a sporting goods retailer. It checks one quarter of bike transactions for a helmet in the same order.
- Store A: 420 bike sales, 290 with a helmet. Attach rate 69%.
- Store B: 380 bike sales, 247 with a helmet. Attach rate 65%.
- Store C: 400 bike sales, 132 with a helmet. Attach rate 33%.
- Online: 600 bike orders, 228 with a helmet. Attach rate 38%.
What the data shows
Store C and online trail well behind. If Store C matched Store B, it would sell about 128 more helmets a quarter, roughly $3,600 in margin.
What it means
The gap sits in what associates offer at the register, and online in what the checkout suggests.
What to do
Coach Store C on a helmet offer with every bike sale, and follow up the 372 online bike buyers with no helmet on their profile.
Want me to build that 372-customer segment and push it to Klaviyo?
Frequently asked questions
What is attach rate in retail?
Attach rate in retail is the share of sales of a main product that also include a specific add-on, such as a case with a phone or a protection spray with leather shoes. It measures how well stores and the website sell the complete purchase, and it is usually tracked per product pair and per store.
Should attach rate count add-ons bought on a later visit?
Track both, but keep them apart. Same-transaction attach rate measures selling at the counter or checkout. A 30-day attach rate, matched by customer, also captures shoppers who came back for the add-on. Mixing them hides whether a store's problem is the conversation at the register or the follow-up after it.
How do I raise add-on sales attach rate without discounting?
Start with placement and prompts. Put add-ons next to the main product, train store associates to offer the one add-on that fits, and show it in the cart online. Bundle pricing helps for slow add-ons, but test it against a no-discount prompt first, since a prompt alone may do the job.