For travelers, nothing feels quite as satisfying as scoring a flight deal that saves hundreds of dollars. Whether you’re planning a summer escape, a business trip, or a spontaneous getaway, knowing the cheapest days to book flights can make all the difference.
In 2025, airline pricing algorithms are smarter than ever, with ticket costs fluctuating daily — sometimes hourly — based on demand, season, and even booking behavior. But while flight pricing may seem unpredictable, patterns do exist. By understanding when airlines adjust fares and how travelers can take advantage, you can consistently find the lowest prices on both domestic and international routes.
Let’s dive deep into the data, insights, and practical tips that reveal when to book your flights to save the most.
Why Flight Prices Fluctuate So Often
Before pinpointing the best days to book, it’s important to understand why flight prices change so frequently. Airlines use dynamic pricing, a strategy that adjusts ticket prices based on demand, time until departure, competition, and even your browsing habits.
A few common factors influencing airfare include:
- Seasonal demand: Prices rise during holidays, summer vacations, and school breaks.
- Advance purchase window: Booking too early or too late can cost more.
- Day of booking: Certain days of the week tend to have lower fares.
- Day of departure: Flying on less popular days can reduce costs.
- Load factor: Airlines continuously monitor how full each flight is and adjust prices accordingly.
Knowing how these variables work together helps explain why booking at the right time can lead to big savings.
The Data Behind the Cheapest Days to Book Flights
In recent years, travel platforms like Expedia, Hopper, and Google Flights have analyzed billions of flight searches to find trends in airfare pricing. Their 2025 reports provide valuable insights that debunk old myths and reveal new patterns.
Sunday: The Best Day to Book Flights
For years, travel experts debated whether Tuesday or Wednesday was the cheapest day to book. However, recent data from Expedia’s 2025 Air Hacks Report confirms that Sunday is now the most cost-effective day to book flights.
According to Expedia:
- Booking on Sunday can save travelers up to 17% on international flights.
- Domestic travelers can save around 6% compared to booking on Fridays or Mondays.
Why Sunday? Airlines tend to release promotional fares over the weekend, and fewer business travelers book on Sundays, leading to lower competition for discounted tickets.
So, if you’re planning a trip, spend your Sunday morning browsing flight deals — it’s statistically the best time to find them.
The Cheapest Days to Fly
Knowing when to book is only half the battle — when you actually fly matters just as much.
Midweek and Saturday Departures Offer Lower Fares
For domestic flights, data shows that Saturday departures are often the cheapest, offering savings of up to 17% compared to popular Sunday flights. Business travelers usually return home on Fridays or Sundays, so Saturdays experience lighter demand.
For international travel, Thursday departures are the sweet spot, often up to 15% cheaper than Sunday departures. Flying midweek or on less popular days helps airlines fill seats, which benefits budget-conscious travelers.
The simple rule:
Book on a Sunday, fly on a Thursday or Saturday, and you’re likely to get one of the best deals available.
Best Booking Windows for Different Trips
Booking on the right day of the week isn’t enough — timing your purchase within the right window before departure is equally important. Airlines follow distinct pricing patterns for domestic and international routes.
For Domestic Flights: 1 to 3 Months in Advance
Data suggests that the best time to book domestic flights is between 28 and 90 days before travel. Booking too early often locks in higher prices before airlines release discounted fares.
For International Flights: 2 to 6 Months in Advance
For long-haul or international trips, start looking earlier — around 60 to 180 days in advance. This window allows you to catch early-bird promotions and avoid last-minute price surges.
If you’re flying to a high-demand destination (like Europe in summer or Asia during festivals), booking 3 to 6 months ahead gives you the best odds for a lower fare.
Why Tuesdays Are No Longer the Magic Day
For years, it was common advice to “book flights on Tuesday afternoon” to find the lowest prices. While that used to be true, modern pricing algorithms have evolved. Airlines now adjust prices dynamically 24/7 based on live demand rather than batch updates once a week.
As a result, the once-famous “Tuesday trick” has largely faded. Studies from Expedia and Google Flights show minimal difference between most weekdays — except Sunday, which consistently offers the best savings.
That said, Tuesdays and Wednesdays still tend to have lower fares for departures, not bookings, since they are off-peak flying days.
Seasonal Patterns: When to Book for Different Times of Year
The cheapest booking days also depend on your travel season. Airfare trends shift based on school holidays, weather, and global travel patterns.
- Spring: Book 2–3 months ahead to catch pre-summer discounts.
- Summer: Prices rise fast — book 3–6 months ahead, ideally on a Sunday.
- Fall: Fares dip — great deals often appear 4–8 weeks before travel.
- Winter: Book early (3–5 months ahead) for holiday travel; otherwise, winter is often the cheapest travel season overall.
In short, the cheapest time to book flights varies by season, but flexibility and Sunday bookings still yield the best outcomes year-round.
How Technology Helps You Find Cheaper Flights
AI-driven travel platforms have revolutionized how we find deals. Tools like Google Flights, Skyscanner, Kayak, and Hopper analyze billions of prices daily to predict fare trends and send alerts when fares drop.
Here’s how to use them effectively:
- Set fare alerts: Let the app notify you when prices for your route fall.
- Use flexible date searches: See how prices change if you fly a day earlier or later.
- Try nearby airports: Flying from or to alternative airports can dramatically lower fares.
- Use private browsing or incognito mode: Prevent cookies from artificially inflating prices.
By combining smart timing with these tools, you can take full advantage of airfare trends without spending hours researching.
Pro Traveler Tips for Finding the Lowest Fares
Beyond knowing the cheapest days, seasoned travelers use a few insider techniques to consistently land great flight deals:
- Book round-trips instead of one-ways – Airlines often price round-trips lower than two separate one-way tickets.
- Use flight comparison engines – Always cross-check multiple platforms before booking.
- Travel during off-peak hours – Early morning or late-night flights can cost significantly less.
- Be flexible with your destination – Use “Everywhere” searches on Skyscanner to see the cheapest destinations from your home airport.
- Avoid last-minute bookings – Prices tend to rise sharply within two weeks of departure.
- Join airline loyalty programs – Members sometimes get exclusive early access to discounted fares.
With these strategies, even long-haul international flights can become surprisingly affordable.
How Airfare Trends Are Changing in 2025
The post-pandemic travel surge brought both increased demand and fluctuating prices. However, data from 2025 suggests airfare is stabilizing as airlines expand capacity and competition increases.
A few notable trends include:
- More flexible pricing: Airlines now use machine learning to adjust fares hourly.
- Dynamic bundles: Some carriers offer discounted “flight + hotel” deals for early bookers.
- Greater transparency: Platforms like Google Flights now highlight carbon emissions and price guarantees, helping travelers book smarter.
These shifts mean travelers who plan early and book strategically — especially on Sundays — stand to benefit the most.
The Takeaway: Timing Is Everything
To recap, here’s what current data and travel insights say about the cheapest days to book flights in 2025:
- Book on Sunday: Best overall savings (up to 17% cheaper internationally).
- Fly midweek or on Saturday: Avoid peak days like Friday and Sunday.
- Book domestic flights 1–3 months in advance, international flights 2–6 months ahead.
- Use flight alerts and flexible date searches to catch spontaneous drops.
- Stay flexible — even a one-day shift in your itinerary can save hundreds.
Airfare pricing may be complex, but travelers who understand timing and flexibility always come out ahead. In 2025, the difference between an average fare and a great one often comes down to choosing the right booking day — and that day is almost always Sunday.
So the next time wanderlust strikes, skip the Tuesday myth, pour yourself a coffee on Sunday morning, and start searching. With smart timing and the right tools, your next adventure could cost a lot less than you think.