Best Time to Book Flights

If you just want the cheat sheet:

• Domestic U.S. flights: book 1–3 months ahead. Savings window commonly ~21–90 days before departure. Sundays tend to be cheapest booking day per Expedia/ARC. Fly mid-week for lower fares.
• International flights: plan 3–6 months ahead overall, with region-specific sweet spots (e.g., Europe ~5–8 months; Asia ~1–7 months, ~120 days; Caribbean longer at ~207 days). Fly Tue/Wed to save.
• Holidays: Google finds Christmas prices lowest roughly 71 days out (late Oct for U.S. travelers). Thanksgiving lows cluster 26–59 days out.

Why timing matters

Airfares are dynamic: prices start high, drop into a “prime booking window,” then climb again inside the final weeks as inventory tightens. Multiple large datasets now converge on months—not days—out as the meaningful lever, plus fly-day choice (mid-week) and booking-day effects (Sundays) that add smaller, but real, savings.

U.S. Domestic Flights: The sweet spot

Book: 1–3 months before departure. Expedia/ARC’s 2025 report shows booking 1–3 months ahead cuts costs vs. last-minute; CheapAir and others frame the “great window” as roughly 21–90 days.

Book-on day: Sunday tends to be the cheapest day to book (up to ~8% vs. Friday in 2025 ARC/Expedia). The old “Tuesday booking” myth is largely debunked.

Fly-on day: Depart mid-week (Tue/Wed) to pay less; Expedia adds Saturday departures are cheaper than Sunday for domestic (≈17% savings).

Holiday exception (domestic):

• Thanksgiving: historic lows ~45 days out; low-price range 26–59 days.
• Christmas: historically lowest around 71 days out (late October).

International Flights: Plan further (but it depends on region)

A recent analysis of 917M fares finds different “prime booking windows” by region. Use these as planning anchors (from U.S. origin):

• Europe: book 5–8 months ahead; “when to buy” median ~160 days. Cheaper month to fly tends to be March; most expensive July. Fly Mon–Wed for best prices.
• Asia: prime window 1–7 months; “when to buy” ~120 days. Cheaper to fly Nov, pricier June; Tue/Wed cheapest fly days.
• Caribbean: unusually long window 1–11 months; “when to buy” ~207 days; cheapest to fly Jan.
• Mexico & Central America: 2 weeks–6 months; median ~70 days.
• South America: 5 weeks–11 months; median ~110 days.
• South Pacific (e.g., Australia/NZ): ~2–8 months; median ~197 days.
• Africa & Middle East: ~3–9 months; median ~199 days.

Tip: For U.S.→Europe specifically, Google’s long-running guidance has shown cheaper prices ~50–179 days out, with a typical “best” around 129 days, so booking 4–6 months is a safe strategy.

Day-of-week myths vs. what actually helps

• Booking day: Sunday has been consistently favorable in ARC/Expedia datasets (2024–2025). The “Tuesday at midnight” trick isn’t a reliable universal saver anymore.
• Flying day: You save more by flying Tue/Wed (often Sat) than by hunting a special booking hour.

Seasonal & event effects

• Peak summer & school holidays: prices surge; book earlier within your region’s window (e.g., Europe at 6–8 months).
• Major events/holidays (Oktoberfest, Christmas, Spring Break): push earlier—Google’s holiday guidance places Christmas purchase in late October for best odds.
• Cheapest months to fly (not book): Expedia’s 2025 data flags August as unusually cheap to travel this year; match this with flexible-date searches.

How to apply this on Sky Engine (and save more)

Search with flexible dates (±3 days). Then target Tue/Wed (or Sat domestic) departures.

Use the right lead time:

• Domestic U.S.: start tracking at 90 days, aim to book 21–60 days out.
• International: start tracking 6–8 months ahead; buy in the region window above.

For holidays: set alerts in late Sept–Oct and book when you hit Google’s low-price window.

Be flexible on airports and routings (e.g., nearby airports or a Thu return) to unlock hidden inventory. (Consistent across Google/ARC insights.)

Don’t over-wait for “last-minute steals.” Data shows prices usually rise inside the final 1–2 weeks.