When to Book Flights to Spend Less: A Timeline
Key points
- Public fare data is historical: BTS averages come from a sample of tickets published with a lag, so no source can name a magic day to buy.
- Set price alerts early. Google Flights tracks routes or specific dates and emails you when prices change or look likely to rise.
- Compare your fare against government averages for your city pair; near or below the historical average is a reasonable signal to buy.
- One-way trips made up 39 percent of fares in BTS third-quarter 2017 data, so price each direction separately before booking.
- Set a buy price when you start watching, book when a fare reaches it, and turn off alerts once you have purchased.
Airfares on the same route can look very different from one week to the next, and none of that is random. Fares respond to how full the plane is, what competitors charge and what is left in each fare bucket when you search. What public data cannot tell you is the exact day to buy. The best a budget traveler can do is work a timeline: watch early, compare against real numbers, and commit when the price fits the budget instead of hoping for one more drop.
Why Timing Matters More Than Any Booking Trick
The federal government keeps long records of what travelers actually pay, and those records show how much timing matters. The Bureau of Transportation Statistics has tracked average domestic fares since 1995, and in the third quarter of 2017 the average domestic fare fell to $336, the lowest inflation-adjusted quarterly fare in the history of those records. Adjusted for inflation, average fares had dropped 28.5 percent since 1995.
The catch is that this data is historical by design. The fare survey behind those averages is a random sample of tickets published with a lag of roughly one to two quarters, and carriers only began reporting a larger share of their tickets, 40 percent instead of 10 percent, as of July 2025. It answers what people paid on a route in a past quarter, not what a ticket costs this afternoon.
The published averages also leave things out. BTS fares include taxes and fees charged at purchase but exclude optional services such as baggage fees. Sales statistics from the Airlines Reporting Corporation cover tickets settled through travel agencies, which does not include tickets bought directly from airlines. ARC processes more than $100 billion in agency air sales a year, so the picture is broad, but it is not complete.
All of this points to one conclusion. No public dataset will hand you a magic booking day, so the reliable tools are a timeline, price alerts and a price at which you are happy to stop shopping.
Six Months Out: Watch, Don’t Buy
Six months before an international trip, the job is information, not a ticket. Fix the basics first: your dates, your destination and the total you can spend, because a cheap flight is worthless if it wrecks the rest of the budget. Our guide to travel budget basics walks through what a trip will actually cost, and our piece on how far ahead to plan a trip helps you match lead time to the kind of trip you want.
Set up price tracking now. Google Flights lets you turn on tracking for a route, for specific dates or for “Any dates” if your schedule is flexible, and it sends an email when the price for a tracked flight or route changes significantly. A few months of watching teaches you what a normal price looks like on your route, and that benchmark drives every later decision.
Three to Two Months Out: The Usual Window for International Trips
Once you have watched for a while, compare your tracked fare against a benchmark you can defend. The Transportation Department’s Office of Aviation Analysis publishes the Domestic Airline Consumer Airfare Report, which covers average prices paid in the top 1,000 domestic city pair markets, and BTS’s fare survey data lets you pull average fares by airport pair.
Use those historical numbers as context, not promises. If a route’s typical fare has run well below what you are being quoted, keep waiting or shift your dates. If the fare in front of you sits near or below the historical average, that is a reasonable signal to buy.
This is also the stage to sort out paperwork. Passports, visas and entry rules can take longer to arrange than the flight itself, and our passport, visa and entry rules checklist covers what to confirm before you pay for anything nonrefundable.
Travel tip
Write down your buy price at the same time you set your alerts. A fare that hits your number is a good outcome, even if it drops lower a week later. Chasing the lowest possible price is how good fares expire.
Six Weeks to One Month: Domestic Flights Enter the Zone
Domestic trips usually need less lead time than international ones, so the same timeline compresses. Start tracking around the time you fix your dates, and expect to make a decision within roughly six weeks of departure rather than six months.
At this stage, compare carefully before you commit:
- Check the same route across several nearby dates. Shifting a trip by a day or two sometimes changes the fare, and flexible dates are your best lever.
- Price each direction separately. In the third quarter of 2017, one-way trips accounted for 39 percent of the fares BTS calculated, and two one-way tickets occasionally beat the round-trip price for the same seats.
- Remember what the fare excludes. Bag fees and other optional charges sit outside the ticket price in the government averages, so add your realistic extras before calling a fare cheap.
- Decide your trade-off between nonstop and connecting itineraries while you still have plenty of seats to choose from.
Demand stays strong, which is worth knowing while you shop. ARC reported 77.4 million passenger trips settled through US travel agencies in the third quarter of 2026, up 3.5 percent from the same quarter of 2025, with quarterly sales of $29.7 billion. Plenty of seats sell before the last minute, and you are competing with all of them.
Last Two Weeks: When Waiting Usually Backfires
The final stretch is where flexible travelers and fixed-date travelers split. If your dates and destination are set, waiting into the last two weeks means shopping from whatever seats remain, and the cheap fare buckets are often gone. Buy before you reach this window.
If you are genuinely flexible, last-minute deals exist, but understand what you are choosing from. You get the leftover seats, on leftover days, to leftover places. That can work for a spontaneous weekend, and our ideas for making the most of a big city on a short visit can help once you land somewhere on short notice. It is a poor strategy for a wedding, a cruise departure or any trip with a date you cannot move.
One more caution for late bookings: leave yourself margin. A tight connection on a last-minute fare saves little and costs a lot when the first leg runs late. The BTS on-time records define a delayed flight as one arriving or departing 15 or more minutes after schedule, which is a normal part of air travel rather than a rare event, so build connection time accordingly.
Set Alerts, Compare Flexibly and Know When You’re Done
Pull the whole timeline together and the method is simple.
- Fix dates and budget first, then start tracking as early as your trip allows.
- Let alerts do the daily work. Google Flights will email you when a tracked price changes significantly, and it also flags when prices on a tracked route are likely to go up, including an estimate of how much and how confident it is in that estimate.
- Check your fare against published averages for your city pair to judge whether a price is actually good.
- Compare two one-way tickets against the round trip, and compare nearby dates before settling.
- Buy at your number. If the fare reaches the price you wrote down months earlier, book it and stop watching. Turn off the tracking emails so the alerts stop tempting you after you already have a ticket.
The airlines earn most of their revenue from fares, but optional fees matter too. BTS data from the third quarter of 2017 shows US passenger airlines collected 75.0 percent of their total revenue from passenger fares, down from 87.6 percent in 1995, which tells you fees and other revenue have grown into a meaningful share. Factor them into every comparison.
Your next step is small: pick your route and dates today, set a price alert on it and write down the fare at which you will buy. Everything else in this timeline follows from that one setup.
Questions travelers ask
Is there one perfect day to book a flight?
No. Published fare data is a historical sample, so any exact-day rule is guesswork. A timeline with price alerts and a set buy price works better than a magic date.
Do fares really get worse in the last two weeks?
They can, and your options shrink as seats sell, so fixed-date travelers should buy earlier. Flexible travelers can sometimes find deals, but they are choosing from leftover seats.
What should I do six months before an international trip?
Fix your dates and budget, start tracking prices on your route, and begin any passport or visa paperwork. You are gathering information, not buying yet.
What is the fastest way to compare fares honestly?
Track your route for a few weeks to learn its normal range, check published average fares for your city pair, and compare two one-way tickets against the round trip.