When Should you Buy Your Airline Tickets? Exactly 8 weeks Before Your Flight

That is according to this formula created by economist Makoto Watanabe.

Like any such rule, I'm sure you'll find plenty of exceptions, but if you don't enjoy spending a lot of time agonizing about when to buy an airline ticket, it's a good rule of thumb to have on hand. In addition to the eight-week rule, Watanabe's formula also suggests that tickets are cheapest in the afternoon, according to The Observer. We can't explain all the science to you [apparently the eight-week formula looks a little something like ∏^A = gU_G + min(k - g, (1 - g)(1 - r))], and the findings, which will be published in the Economic Journal, aren't yet available.

Also according to Watanabe the best time to buy the tickets is in the afternoon. I wonder why that is? I figure that the fare rate meetings at the Airlines occur in the morning and they update the servers after lunch. I guess this is so people coming home from work can book their non-business flights at 7 - 8 PM their time. I figure the selection is better in the afternoon because the fares have just been updated and all the seats are in play.