Expedia’s 2025 industry report shows booking on Tuesday saves money, August is the cheapest month to fly, and Sunday is the cheapest day to book. These aren’t internet myths — they’re statistically verified patterns from actual airline pricing data.
The travel industry has a small, persistent gap between what professional travel agents and bookings analysts know about flight pricing and what most consumers know. Some of the gap exists because the airline industry deliberately makes pricing opaque (dynamic pricing, hidden fees, complex fare classes). Some of it exists because the patterns that consistently produce savings aren’t intuitive — and run counter to what booking sites’ marketing implies.
In January 2025, Expedia released its annual “Air Hacks Report,” produced in partnership with Airlines Reporting Corporation (ARC) and aviation data company OAG. The report analyzed billions of passenger flights operated by more than 480 airlines in over 235 countries. Its findings — combined with insights from working travel agents quoted in published industry interviews — produce a clear picture of what consumers consistently get wrong.
Here are seven of the most-cited gaps.
1. The cheapest month to fly is August, not the off-season you’d expect
According to the Expedia 2025 Air Hacks Report, August is the cheapest month to travel domestically and internationally. February and March are the most expensive. Traveling domestically in August versus February can save travelers 12%. Flying internationally in August versus March can save up to 7%.
This is genuinely counter-intuitive. Most consumers assume August is expensive because of summer vacation demand. The data shows the opposite. The reason, according to industry analysts, is that the lowest-demand August routes (those not feeding into vacation hotspots) drag the overall average lower than the highest-demand February business travel routes.
For practical purposes: if you’re a flexible traveler, August produces better fares on average than the months consumers typically associate with “off-season” travel. The exception is specific high-demand routes (anything to Europe in early August, anything to the Caribbean during specific holiday weeks).
2. Sunday is the cheapest day to book — and Tuesday-Wednesday is too
The Expedia report identified Sunday as the cheapest day of the week to book flights. Many travel agents and frequent flyers have long recommended booking on Tuesdays or Wednesdays, but the 2025 data revised this. Sunday booking, according to the analysis, captures a brief Sunday-evening window when airlines update fares for the upcoming week.
A frequent flyer’s standard practice should therefore be: search Sunday evening, book Sunday evening if a route is at a reasonable price. If you miss Sunday, Tuesday and early Wednesday morning produce the next-best results.
The mechanism is straightforward: airline pricing algorithms run on weekly cycles. Friday-Saturday-Sunday morning sees the highest booking volume from leisure travelers, often with prices reflecting that demand. Sunday evening is when carriers reset for the upcoming week. Tuesday is when competing airlines see Monday’s pricing and adjust to compete.
3. The actual best day to fly is Thursday, saving 17% over Sunday
Beyond when you book, when you fly matters even more. The Expedia 2025 report found that flying on Thursday instead of Sunday saves 17%, regardless of fare class and destination. For domestic travelers, departing on Saturday instead of Sunday saves the same 17%. For international travelers, Thursday is the cheapest day to fly, saving 15% compared to flying on a Sunday.
The mechanism: leisure travelers concentrate on Friday-Sunday departures and Sunday-Monday returns. Mid-week travel has lower demand and therefore lower prices. Business travelers historically traveled Monday-Friday but are increasingly traveling Tuesday-Thursday, leaving Friday and Sunday as the “premium” days.
For travelers willing to flex, departing Thursday and returning Tuesday produces meaningfully cheaper flights than departing Saturday and returning Sunday — even on the same route, same airline, same season.
4. Book domestic flights 1-3 months out, international 18-29 days out
This finding from the 2025 report contradicts both extremes of conventional wisdom. The widely-cited “book 6+ months in advance for the cheapest fare” rule is wrong for international travel. So is the “wait until the last minute for deals” approach.
The Expedia data shows: booking domestic flights 1 to 3 months in advance saves 25% compared to last-minute bookers. Booking international flights 18 to 29 days before departure saves up to 17% versus booking three months out or more.
The mechanism for international travel surprised some analysts: airlines apparently set early international fares conservatively (high), then drop prices during a specific 2-4 week window before departure when remaining inventory becomes a concern. Booking too early misses this drop. Booking too late risks sold-out flights and last-minute price spikes.
For travelers booking from the United States: domestic flights book best 6-12 weeks out. International flights book best 3-4 weeks out. Outside those windows, you’re paying a premium for either certainty (very early bookings) or risk (very late bookings).
5. Airlines and booking sites use cookies to raise your prices
This is the practice travel agents universally warn clients about and that most consumers don’t believe. According to multiple working travel agent interviews and the published documentation of how airline pricing systems work: yes, airlines and booking sites track your browsing behavior, and yes, prices on the same flight can rise after multiple searches.
The mechanism is dynamic pricing. Airlines run continuous demand-monitoring algorithms that detect when a specific route is being researched intensively. If you’ve searched “Newark to London” five times in a week, the system flags you as a high-intent buyer and adjusts the price upward, expecting you’ll buy anyway.
The travel agent fix: clear your cookies before booking, or use incognito/private browsing mode for all flight searches. Some travel agents use multiple devices to compare prices — checking the same flight on a friend’s phone they haven’t searched before, to see the “true” baseline price.
6. Morning flights are 57% less likely to be cancelled
This is one of the most underused pieces of practical travel knowledge. According to the 2025 Expedia/Airlines Reporting Corporation data, flights departing after 9 PM have a 57% higher chance of being cancelled compared to those leaving earlier in the day. Flights departing between 9 AM and 3 PM face the lowest rate of cancellations.
The mechanism: cancellations cascade through the day. A delayed morning flight in Chicago can disrupt the same aircraft’s afternoon flight in Denver, then its evening flight in San Francisco. By the time you reach late evening, accumulated weather, mechanical, and crew-time issues have built up across the airline’s entire network.
For travelers booking flights with tight connections or critical arrival times: morning flights, ideally before noon, dramatically reduce your cancellation risk. The August/September month data shows the same pattern — those months see the lowest rate of cancellations (1.2%) and shortest average delays.
7. The “personal item” loophole is closing
This is the practical insider knowledge most travel agents have started giving clients in 2025-2026. For years, travelers used oversized backpacks, structured totes, and hybrid carry-on/personal-item bags to avoid paying for checked bags or even for full-size carry-ons. Airlines are now actively cracking down.
According to multiple 2026 industry reports and direct travel agent observations, gate agents are being instructed to enforce personal-item size limits more strictly. New automated bag-sizer machines are being installed at boarding gates that measure bags to the millimeter. Bags that exceed the airline’s specific personal-item dimensions are being flagged as carry-ons (with fees) or checked bags (with higher fees).
The fees themselves have escalated: gate-checked bag fees now run $35-$65, while online-paid checked bags at ticket counters run $30-$50. American Airlines specifically updated its fees effective April 9, 2026: $50 for the first checked bag ($45 if paid online), $60 for the second ($55 online).
The travel agent recommendation: if you’ve been using an oversized “personal item” to avoid fees, reconfigure now. Use a structured bag that maintains its shape (rather than a stuffed-to-bursting backpack), measure your bag against your specific airline’s published personal-item dimensions, and pay attention to the difference between a “personal item” (must fit fully under the seat) and a “carry-on” (overhead bin). Several airlines now block overhead bin access entirely on basic economy tickets unless you pay extra.
What this knowledge actually saves you
Apply all seven of these patterns to a single international trip and the cumulative savings can be substantial. A traveler who:
- Books on Sunday evening (1-3% savings)
- For travel in August (7-12% savings)
- Departing Thursday rather than Sunday (15-17% savings)
- Booking 2-3 weeks before departure for international (up to 17% savings)
- Using incognito browsing to avoid price-tracking
- Selecting morning flights to reduce cancellation risk
- Following carry-on rules carefully to avoid gate fees
…will pay meaningfully less than a traveler who books on a Friday afternoon, in March, departing Sunday, six months out, after multiple searches in regular browsing.
A travel agent’s actual job, increasingly, is helping clients navigate exactly these compounding factors — and access wholesale rates through industry booking systems that consumers can’t see. For the majority of routine domestic trips, an informed consumer using a comparison site can match what a travel agent would book. For complex international itineraries, multi-stop bookings, or trips during peak demand, a working travel agent can often save more than their commission costs.
The biggest mistake travelers make, according to agents quoted in industry interviews, is treating flight booking as a single transaction rather than a strategic decision with multiple optimizable variables. The savings from just one of these factors might be 5-10%. Stacking them produces 30-50% savings on the same flight.
