Short answer: metasearch platforms mostly sell clicks in an auction, and an advertiser's maximum sustainable bid is set by simple algebra - the margin earned per booking multiplied by the rate at which clicks become bookings. Everything else is detail. High downstream conversion lets you outbid rivals for the same click; poor conversion makes every position unaffordable. That is why conversion rate, not bid tactics, decides who wins metasearch.
How metasearch makes money
A metasearch engine - Skyscanner, Kayak, Google Flights, trivago and their peers - aggregates prices from OTAs, airlines and hotels, and charges those advertisers for the demand it forwards. (Note the vocabulary: "meta" here means metasearch, comparison shopping; it has nothing to do with Meta Platforms or Facebook advertising.) The main billing models:
| Model | Advertiser pays when | Risk sits with |
|---|---|---|
| CPC (cost per click) | A traveller clicks through to the advertiser's site | Advertiser - clicks may not convert |
| CPA / commission (cost per acquisition) | A tracked booking completes, or a stay is consumed | Metasearch - clicks are free if nothing books |
| CPI-style referrals | A defined event such as an app install | Shared, depends on the deal |
| Sponsored placement | Fixed or premium fee for promoted positions | Advertiser |
CPC dominates flight metasearch. CPA exists mainly where the platform trusts the partner's tracking, and the industry has been drifting toward auction models: Google's Ads Help centre ("Commission-based bid strategies in hotel ads to sunset") records that commission-based bidding for hotel ads was deprecated on 20 February 2025, pushing hotel advertisers onto CPC-style and automated bid strategies. Always check the current programme documentation, because these mechanics change.
The CPC auction from the demand side
When a traveller searches Delhi to Dubai, the metasearch platform holds, in effect, an auction for the ranking of offers. Your position depends on your bid, but also on your quoted price (cheaper offers attract the clicks the platform is selling) and quality factors such as price accuracy - quote a fare on the comparison screen that your site cannot honour at checkout and platforms will penalise or delist you. So the demand-side levers are three: what you bid, how sharp your quoted fares are, and how faithfully your booking flow honours the quote.
Bids are typically managed by route, market and device, and the auction is dynamic: a route's clicks cost more in peak booking season and less in the trough. Sophisticated advertisers re-bid continuously against their own conversion data, which is a large part of what an OTA's marketing team actually does all day.
Bid-to-margin arithmetic
The core equation is short enough to write on a napkin:
Break-even CPC = margin per booking x conversion rate from click to booking.
Read it in both directions. If you know your margin per booking and your site's conversion rate, you know the most you can pay for a click and still break even; bid below that and clicks are profitable, above it and you are buying losses. Rearranged, it also tells you the conversion rate you must achieve to afford the market's going click price:
Required conversion rate = market CPC / margin per booking.
Two refinements matter in practice. First, use contribution margin - the fare markup or commission plus ancillaries, minus payment costs, GDS or API fees per segment and support cost per booking - not gross revenue. Second, include repeat business: if a meaningful share of first-time bookers return direct, the affordable CPC on the first booking rises accordingly. Just be honest about that share; assuming loyalty you have not measured is how advertisers slowly bleed out.
Why downstream conversion decides viability
Look at the equation again: conversion rate multiplies everything. Two OTAs buying the same click at the same price, with the same margin per booking, are not in the same business if one converts clicks at twice the rate of the other - the stronger converter can profitably bid roughly twice as much, take the visibility, and still earn more per click. This is why metasearch is often described as a conversion-rate contest with an auction attached.
Downstream conversion for flight traffic is mostly determined by mundane engineering: the quoted fare still being available at checkout (fare accuracy and cache freshness), page speed on mobile, payment success rates in the traveller's market, and the absence of surprise fees between the comparison screen and the confirmation. Every one of those is a build-quality question. It is the practical argument for treating your flight booking engine and flight API integration as the profit centre of a metasearch strategy, not a cost line - and it is closely tied to how you manage search traffic against supplier limits, covered in our guide to the look-to-book ratio.
CPA and hybrid models
Under CPA, the platform takes the conversion risk and gets paid per tracked booking or consumed stay. Advertisers with weak or unproven conversion prefer it for obvious reasons; platforms grant it selectively because it pays them nothing for clicks that die on a slow checkout they do not control. Where both models exist, the arithmetic converges: a platform's expected revenue per click under CPA is your conversion rate times the commission, so strong converters end up paying more per booking under CPA than they would have paid in the auction. CPA is training wheels - useful while you build conversion data, rarely the cheapest place for a good operator to stay. The direction of travel, as the Google hotel ads change shows, is toward auctions and automated bidding, which rewards exactly the operators who know their numbers.
The dashboards to watch
Whether you buy metasearch traffic or send traffic to advertisers, the same handful of numbers describe the health of the machine:
- Conversion rate by route and market - the master variable; segment it, because a blended average hides the routes that lose money
- Effective margin per booking after payment, supplier and support costs
- Break-even CPC vs actual CPC per segment - the gap is your profit per click, and it should be on one screen
- Fare accuracy - the percentage of clicks where the quoted price survives to checkout; platforms track it, so should you
- Cost of sale - metasearch spend as a share of booked margin, trended weekly
- Payment success rate by market - a silent conversion killer, especially in India and other markets with bank-level friction
Run these from your own data warehouse, not just the platforms' consoles: the platform reports clicks sold, but only your systems know what those clicks became.
The view from the supply side
Flip the model and you have the business case for owning a metasearch or comparison site: the site owner earns the CPC or referral fee that advertisers pay. Every equation above still applies, one step removed - your inventory is traveller attention, and its value depends on the booking intent of your audience and the conversion quality of the partners you send them to. A niche comparison site with high-intent traffic can out-earn a bigger, shallower one. If that side of the trade interests you, our pages on meta flight websites and flight aggregator websites cover what gets built, and the guide to how flight metasearch engines work covers the plumbing underneath.
This article is general information about travel technology and online marketing. It is not legal, tax or financial advice, and advertising platform policies change often. Check the current policy documents and take professional advice for your own situation.