Attach Rate
Attach rate is how often the companion item rides along with the primary sale, the accessory engine’s gauge.
What attach rate is
Attach rate is how often the extra rides along: the share of primary purchases that include a companion item, the case with the phone, the warranty with the appliance, the refill with the device, accessories attached per main sale.
Why attach rate matters
Accessories and add-ons usually carry the fattest margins in the catalog: the primary product wins the customer, the attachments make the money. Attach rate is that engine’s gauge, and moving it a few points, on traffic already bought and shipping already paid, is among the cheapest profit a store can find.
Raising the rate
- Pair by data: what actually gets bought together, not what should
- Offer at every altitude: product page bundles, cart add-ons, checkout bumps, post-purchase
- Frame as completion: “everything you need to start” beats “you might also like”
- Track per primary product: attach lives at the SKU level, not the store level
Frequently asked questions
Attach rate vs basket size: what’s the difference?
Composition versus count: basket size counts items per order, attach rate asks whether the right companion joined a specific primary purchase. A store can grow baskets with discounts while attach on its flagship stays flat, which is exactly the case the metric exists to catch.
What’s a good attach rate?
Category-bound and product-specific: high-consideration primaries with obvious companions attach far more than standalone goods. Benchmark each hero product against its own history, and let the best-attaching pair teach the merchandising for the rest.