Somewhere around 2015, the incognito browser tip went fully viral: airlines track your searches, the theory goes, and raise prices when they see you coming back. Clear your cookies, go private, and you’ll see lower fares. It’s been repeated so many times that most travellers treat it as settled fact.

It’s not. Airlines price dynamically based on seat inventory, route demand, booking window, and time of day - not individual browser sessions. The fares you see vary because inventory genuinely changes by the minute, not because the airline has identified your laptop. A few studies and consumer advocates have looked into this directly, and the evidence for personalised fare targeting based on search history is thin at best.

That said: use incognito anyway.

Not because it lowers prices, but because logged-in browsers sometimes autofill saved payment methods or accounts that can skew comparison results, and because cached data occasionally causes display errors on booking sites. It’s a cleaner environment for searching. Just don’t expect it to magically surface cheaper fares.

What Actually Affects the Price You See

The booking window matters more than almost anything else for international flights. The general pattern - book too early or too late and you pay more, with a sweet spot somewhere in the middle - holds up reasonably well for long-haul routes. For short-haul European or Southeast Asian flights on low-cost carriers, last-minute can occasionally go either way, but it’s not a strategy worth gambling on.

The day and time you search does seem to produce some variation, though this is harder to pin down with certainty. Mid-week searches and off-peak hours have anecdotally produced lower fares for some travellers, but this is inconsistent enough that it shouldn’t drive your planning.

What’s more reliable: use Google Flights’ price calendar view and set a fare alert on the specific route. Let the tool do the watching. Check directly on the airline’s own site once you’ve identified a good price - sometimes the booking fee added by third-party aggregators quietly eats the difference you thought you were saving.

The Bigger Mistake

Most people anchor on the departure price and ignore the return leg entirely until it’s too late. If you’re booking a round trip separately - outbound one carrier, return another - price both directions before committing to either. The cheap outbound fare that traps you into an expensive return is a very old trick the internet never quite got around to making viral.