How airfares are actually priced

Airlines don't price a seat. They price a forecast — and every ticket you've ever bought was the output of a system guessing how many people will want that flight, how much they'll pay, and when they'll decide.

The fare bucket system

Every economy cabin is carved into booking classes, usually lettered: Y, B, M, H, Q, V, W, S, T, L, K and so on. Each letter is a fare level with its own price and rules. The cheapest buckets have a small allocation; the most expensive — full-fare Y — is effectively unlimited.

When you search, you're seeing the lowest bucket that still has seats. When those sell, the price "goes up" — but nothing was repriced. The cheap bucket closed and the next one became the lowest available.

This is why a fare can jump $120 between your first search and your second ten minutes later, and why it can drop back the next day: the airline's revenue-management system constantly reopens and closes buckets as its forecast changes.

What moves the forecast

• Days to departure. Leisure travellers book early and are price-sensitive; business travellers book late and aren't. Airlines keep more seats back as the date approaches because the late bookers pay more.
• Load on the flight. A flight filling faster than its historical curve closes cheap buckets early. One filling slowly opens them.
• Competition on the route. A new low-cost entrant on a route can halve fares overnight. A competitor cancelling a flight does the opposite.
• Day of week and season. Friday and Sunday evenings, school holidays and events price high on the day they fly — not the day you book.

Myths worth dropping

"Tuesday is the cheapest day to book." Years ago airlines filed fare changes in weekly batches; Tuesday was when the sales landed. Fare filing is now continuous and automated. The day you book barely matters; the day you fly matters a lot.

"Clearing cookies gets a lower fare." Repeated searches don't raise your price. What you're seeing is the bucket mechanism above, or a cached result expiring. Logged-in members occasionally see lower fares, never higher ones.

"Last-minute fares are cheap." For hotels and cruises, often. For flights, almost never — the late-booking seats are reserved for people who'll pay full fare.

What actually works

1. Search a date range, not a date. The trip planner shows cheapest dates on a route; shifting by a day or two is the single biggest lever.
2. Book domestic 1–3 months out and long-haul international 2–6 months out, as a rough rule. Earlier isn't better: fares often open high and drift down before the final climb.
3. Watch for the fare rules as much as the price. A "basic" fare that charges for a cabin bag and prohibits changes is often not the cheap option once you add what you need.
4. If your plans are firm and the fare is within your budget, buy it. Waiting for a drop is a bet you'll lose more often than you win.