Cost per booking (CPA)

Cost per booking is ad spend divided by the bookings it brought. Ad platforms usually call it cost per acquisition or cost per action (CPA). Google gives the formula as marketing cost ÷ number of actions.

For travel brands, the hard part is counting the bookings. A booking can come days or weeks after the click, by phone or through an agent. So the count depends on tracking and on the attribution window.

Example: a cruise line divides a month's native advertising spend by the bookings traced to those ads. Phone bookings that follow a brochure request need their own route back to the ad.

Related: cost per inquiry · click-to-booking rate · attribution window