In short
Attach rate is the share of bookings that include an additional paid item beyond the base trip. In travel, it shows how often travellers add options such as seats, bags, or service products. It matters because revenue improves when more confirmed bookings carry at least one relevant extra.
Why the metric is useful
Attach rate is a practical way to judge whether merchandising is working. It is not just a measure of how many people saw an offer. It asks whether an offer joined the booking.
That distinction matters because a travel seller can create many impressions without creating much value. A traveller may scroll past a weak offer, ignore a confusing one, or abandon a cart that asks for too much too soon. Attach rate keeps the focus on outcomes.
What changes attach rate
Three levers usually matter most: relevance, timing, and clarity. Relevance asks whether the option fits the itinerary. Timing asks whether the traveller is in a decision moment. Clarity asks whether the traveller understands what they are buying and why it changes the trip.
Price matters too, but it is rarely the whole story. A low-price item with poor timing can be ignored. A higher-price item with obvious value can feel easy to justify once the trip is confirmed.
How to read it with care
Attach rate can rise for the wrong reason if the offer is forced into the path or described unclearly. That may create short-term sales and long-term service cost.
The better question is not only whether attach rate rose. It is whether the extra items were understood, paid for willingly, and carried through to the rest of the traveller experience.
Frequently asked questions
What does attach rate measure?
It measures how often a booking gains an additional paid item, such as a seat, bag, or service option.
Is attach rate the same as conversion rate?
They are related but not identical. Conversion rate usually measures a purchase action, while attach rate measures whether an extra item joined the booking.
Why does relevance affect attach rate?
A traveller is more likely to add an option when the timing, itinerary, and explanation make the value obvious.