The Cheapest Day to Fly: We Analyzed 368 Routes
Every route in our database, one question: which day costs least? The answer barely varies.
⬇ Download full dataset (CSV, 368 routes)How we did it
We pulled pricing metadata for all 368 routes in the Flighko database — spanning US domestic, European, Asian and intercontinental corridors — and recorded the historically cheapest departure day and best booking month for each route. Fares are round-trip economy estimates in USD, updated August 2026. The full per-route table is available as a CSV download for journalists, researchers and travel writers.
The 10 cheapest routes in our database
| Route | Round trip from |
|---|---|
| Singapore → Johor Bahru | $25 |
| Los Angeles → San Diego | $40 |
| Seattle → Portland | $40 |
| Austin → Houston | $45 |
| Barcelona → Madrid | $50 |
| Kuala Lumpur → Singapore | $50 |
| Los Angeles → Las Vegas | $50 |
| Atlanta → Charlotte | $55 |
| Denver → Salt Lake City | $55 |
| New York → Nashville | $110 |
And the priciest corridors
Ultra-long-haul routes with little competition top the list. Sydney–London leads at $900 round trip — nearly 36× the cost of flying Singapore–Johor Bahru.
| Route | Round trip from |
|---|---|
| Sydney → London | $900 |
| Buenos Aires → Madrid | $700 |
| Seoul → New York | $700 |
| Sydney → Dubai | $700 |
| Tokyo → New York | $700 |
| Paris → Tokyo | $680 |
Why is Tuesday the cheapest day to fly?
Airline pricing follows demand. Business travellers book Monday mornings and fly midweek-to-Thursday; leisure travellers crowd Fridays and Sundays. Tuesday sits in the trough between these waves, and airlines drop fares to fill seats. On 365 of our 368 routes, Tuesday departures priced lowest — the exceptions were two Wednesday-cheapest routes and one Friday outlier.
Frequently asked questions
What is the cheapest day of the week to fly?
Tuesday is the cheapest departure day on 365 of the 368 routes we analyzed (99%). Wednesday is a close second. Friday and Sunday are consistently the most expensive days to fly.
What is the best month to book flights?
October is the best booking month on 351 of 368 routes in our dataset, as airlines price for the post-summer lull. January and September follow.
How much does the average flight cost in 2026?
Across the 368 routes we track, round-trip economy fares average $207. US domestic routes average $149 while international routes average $251.
What is the cheapest flight route in the world?
In our dataset, Singapore to Johor Bahru is the cheapest at $25 round trip, followed by Los Angeles–San Diego and Seattle–Portland at $40.
Why is Tuesday cheaper for flights?
Business travelers book Monday mornings and fly Thursday; leisure demand peaks Friday–Sunday. Tuesday sits in the demand trough, so airlines price it lower to fill seats.
How far in advance should I book a flight?
For most routes in our analysis, 4–8 weeks ahead gives the best balance of fare and availability. Ultra-long-haul routes (Sydney–London, Tokyo–New York) reward booking 10+ weeks out.