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How Flight Search Actually Works (And Why Every Site Shows You a Different Price)

Search the same flight on five different websites and you'll often get five different prices for what's supposedly the same seat. None of the sites are necessarily lying to you. They're just not all doing the same thing under the hood — "flight search" isn't one technology, it's three quite different ones wearing the same kind of search box.

The three kinds of "search"

1. The airline's own website. This is the simplest case: the airline is querying its own inventory system directly. What it shows you is authoritative — for that one airline. It has no idea what anyone else is charging, because it isn't looking.

2. Live multi-airline search. Some tools query many airlines' systems in real time, in the moment you hit search, and get back live availability and pricing across all of them at once. This is genuinely live — the number you see reflects what's actually bookable right now, not what was bookable at some earlier point. This kind of search costs the provider money every time someone uses it, because it's a real request to real airline systems, not a lookup from a local database.

3. Cached comparison / metasearch. A large share of flight comparison sites work differently: they pull from a data feed that gets refreshed periodically — sometimes every few hours, sometimes once a day — rather than querying live on every single search. What you're shown is a snapshot, dressed up to look like a live result. Click through, and you're usually redirected to book the actual ticket somewhere else entirely, at whatever the live price turns out to be by then.

This isn't necessarily dishonest — it's a legitimate, much cheaper way to run a comparison site, since a live query costs real money and a cached feed doesn't. But it does mean the number on screen and the number you'd actually pay can quietly drift apart, especially on routes where prices move fast.

Why this is worth knowing as a traveler

None of this is really about which site has better design. It's a cost decision each provider makes: live data is accurate but expensive to provide; cached data is nearly free but can go stale. Most sites you use day to day have picked a spot on that trade-off without ever telling you which one.

That's the actual reason "the price changed when I clicked through" happens so often — on a lot of sites, the number you searched was never quite live to begin with.

Rough ways to tell which kind you're looking at

• Does clicking a result take you to a checkout on the same site, or bounce you out to book elsewhere? Redirect-to-book is common on cached comparison sites.
• Does it show specific, seat-level detail — exact baggage allowance for that fare, exact departure time down to the minute — or a generic policy blurb ("baggage varies by fare")? Specific detail usually means a live query actually happened; vague detail often means it didn't.
• Does searching the same route twice, minutes apart, ever return a different number? If it never changes even when you'd expect real fare movement, you might be looking at a cache that hasn't refreshed yet.

None of these are proof on their own, but together they're a decent tell.