Cost per Acquisition (CPA)

Cost per acquisition (CPA) is a marketing metric that measures the average cost of acquiring a customer. It is calculated by dividing the total cost by the total conversions; for a hotel or vacation rental campaign, the conversions are usually its bookings (What is Cost Per Acquisition? (Amplitude glossary)) (Google Ads Metrics Glossary (Optmyzr)).

Last updated: November 2026

How cost per acquisition works

CPA shows up in two forms: as a result an advertiser measures after a campaign, and as a price the advertiser bids or pays. Google Ads uses the second form. In its Target CPA bid strategy, the letters stand for cost-per-action, and the advertiser sets the desired average cost per conversion; Google Ads then tries to keep the cost per conversion equal to that target (About Target CPA bidding (Google Ads Help)).

Hotel metasearch has moved in two directions on this. Google has ended commission-based bidding for hotel ads, the model under which a hotel paid Google a fee only when a guest completed a stay booked through an ad (Google's commission-based hotel ads are gone (Mews)). Our Google Hotel Ads page covers what hotels use there now.

trivago went the other way. Since September 1, 2025, it has phased out cost-per-click bidding for hotel campaigns, which now run exclusively on a CPA model with a global minimum net CPA of 10% (trivago says goodbye to CPC: CPA takes over (Paraty Tech)). The change does not affect trivago Sponsored Listing, which stays on cost per click (Upcoming changes to trivago CPC campaigns: FAQs (Bookassist)). The word "net" matters: for independent hotels, trivago turned its Gross CPA model into a Net CPA model that takes cancellations into account when charging commissions, and in January 2024 it added Net CPA on Consumption (trivago improves its commissions programme: Net CPA (Mirai)).

On trivago, then, CPA is a percentage of the booking's value, while in Google Ads it is an amount of money per conversion. The What is trivago? and What is metasearch? pages explain how these sites send guests to a hotel.

Why cost per acquisition matters for hotel distribution

Every channel that brings a hotel a booking has a cost attached, and the gap between channels can be wide. Some hotels spent as much as 35% of guest-paid revenue on acquiring customers, in Kalibri Labs data reported around 2016 to 2017 (Consumer acquisition costs in hospitality too high and growing (Revenue Hub)). The same data showed OTA business required as much as 6.5 times the acquisition investment of direct business, with global distribution systems at roughly five times (Consumer acquisition costs in hospitality too high and growing (Revenue Hub)).

OTA bookings cost more to acquire because a hotel keeps reacquiring the same guests, and merchant and opaque OTA commissions are one of the largest reservation cost drivers (Demystifying the Digital Marketplace (HSMAI)).

Putting the channels on one scale is the practical use of CPA. A paid-search campaign that drives direct bookings has a CPA you can work out from spend and bookings. An OTA commission is a percentage the hotel pays for each booking an OTA delivers, so it can be read as that channel's cost per acquisition. A metasearch CPA sits between the two. Tracked side by side, by channel, these numbers belong with the rest of a property's hotel KPIs.

The research figures above are older. We found no recent published research on acquisition costs for hotels, and none for vacation rentals, so a property's own booking and spend data is the best guide to its current CPA by channel.

Cost per acquisition compared with CPC, OTA commission, ROAS and CAC

MetricWhat it measures or chargesWhere hotels see it
Cost per acquisition (CPA)The average cost of one conversion: total cost divided by conversionsGoogle Ads Target CPA; trivago's net CPA, set as a percentage
Cost per click (CPC)A charge for each click, whether or not the guest bookstrivago Sponsored Listing; Google's hotel ads after commission bidding ended
OTA commissionA percentage of each booking paid to the OTAEvery booking taken through an OTA
Return on ad spend (ROAS)Revenue (conversion value in Google Ads) divided by the cost of ads Google Ads Metrics Glossary (Optmyzr)Judging whether ad spend earns more than it costs
Customer acquisition cost (CAC)Total acquisition costs to win a guest, across every channelHotel-wide distribution cost, as in the research above

Frequently asked questions

What is the cost per acquisition formula?
Divide the total cost by the number of conversions. Google Ads shows the same arithmetic in reverse for advertisers who choose to pay for conversions: with a Target CPA of $10 USD and 10 conversions during a month, the bill is $100 USD. A hotel can apply the formula to any channel, as long as cost and bookings are counted over the same period.
What is cost per customer acquisition?
Cost per customer acquisition, often called customer acquisition cost (CAC), is the wider measure: total acquisition costs to win a guest, across every channel and not only one campaign. HSMAI and Kalibri Labs estimated hotels' total acquisition costs at between 15% and 25%. That figure describes the whole cost of acquiring a guest, so it sits closer to CAC than to the CPA of one ad campaign.
What is a good cost per acquisition for a hotel?
A good CPA leaves profit once the stay is paid for, so it depends on what the booking earns. On percentage-based metasearch, the floor and the guidance are public: trivago set a global minimum net CPA of 10% and recommends 12%. At 10%, €5,000 of confirmed bookings from trivago campaigns costs €500 in commission. Compare that with the cost of the same bookings on other channels.
Is an OTA commission a cost per acquisition?
In effect, yes. The difference is who sets the price: the channel sets its commission, while a hotel bids or measures CPA on its own campaigns. Commission rates, and what drives them, are covered on our OTA commission page.

Related terms

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Where Jetstream fits

CPA only compares channels fairly when every channel is selling the same rooms at the right rates. Jetstream builds an AI channel manager that connects a property's systems to the channels where guests book and keeps rooms, rates and availability accurate on each one, managed from one place.

See Jetstream's AI channel manager Book a demo