Glossary · Travel distribution
Look-to-book ratio
The look-to-book ratio is the number of availability or price searches a travel system answers for each booking it receives — written as, say, 1,000:1 — and it measures how much computing an airline, hotel or distribution system spends to sell one trip.
Reviewed 30 Oct 2026
Why the ratio costs money
Every search has to be priced. In the classic model a GDS does that from filed fares; with NDC the airline builds each offer itself, at request time, so the cost of a high ratio lands on the airline's own systems. IATA's 2019 study of NDC in the leisure market called cost "by far the most significant challenge" arising from high ratios, ahead of infrastructure scalability and response times.
Typical levels
| Channel | Look-to-book reported in IATA's 2019 study |
|---|---|
| Airlines' own websites | 100:1 to 300:1 |
| OTAs and metasearch, best case | 1,000:1 |
| OTAs and metasearch, commonly | Above 10,000:1 |
| Target interviewees considered achievable | 5,000:1 to 10,000:1 |
The same study found ratios multiplied by three to five when an airline lets metasearch engines poll its offer system from the very first search, and expected them to stay in the several thousands to one.
How the industry manages it
- Caching offers and answering repeat searches from the cache.
- Limits on searches per booking written into agreements with sellers.
- Airline profiles that tell sellers which origin–destination pairs an airline will answer for, so irrelevant requests are not sent.
- Filtering out unreasonable itineraries before they are priced.
What it means for fare collection
Searches on a public website cost the airline the same computation as any other search that does not end in a booking. Collect only the routes and dates you need, at a cadence the question justifies, and reuse results rather than re-querying — the practical version is in collecting travel data responsibly and flight availability.
FAQ
Questions
Something not covered? Write to contact@arcproxies.io.
What is a good look-to-book ratio?
It depends on the channel. IATA's 2019 study reported 100:1 to 300:1 on airlines' own websites and above 10,000:1 as common for OTAs and metasearch, with 5,000:1 to 10,000:1 seen as achievable there with monitoring.
Why do airlines limit look-to-book ratios?
Because answering searches costs computing capacity and, in some channels, fees, while only bookings bring revenue. Limits in seller agreements keep the cost per booking in check.
Does price scraping affect an airline's look-to-book ratio?
Automated searches on public pages add load in the same way that searches without a booking do. That is a reason to keep collection to the routes, dates and frequency you actually need and to cache results.
Do hotels have look-to-book ratios too?
Yes, the idea applies to any travel inventory searched far more often than it is booked, including hotel availability requested by OTAs and metasearch sites.
Sources & review
Last reviewed by the ARC Proxies team. Prices are read from the live catalog at build time.
In practice