The way airlines are pricing tickets has changed. You can often buy cheap fares at the last minute now. You used to have to buy 14 or 21 days in advance for the lowest fares, and that’s one way airlines separated business from leisure travelers, but ultra low cost carriers like Spirit, Frontier and Allegiant have changed that model and advance purchase alone is no longer a guaranteed way for airlines to charge business travelers more.

You can still get the best airfare deals in advance though (last minute can be a risk). And those last minute deals are especially unlikely to happen around holidays, because planes will be full.

There’s No Magic Bullet Day to Buy, Here’s How Airfares Work Around the Holidays

It isn’t as simple as ‘waiting until 54 days prior to departure’ to buy. Start to look at leisure travel about 3 months out for most trips. Peak holiday travel is usually cheapest earlier than when leisure tickets are cheapest because everyone else is doing the same, snapping up the lowest fares.

Airfares are a combination of fare rules and prices for a given city pair. These change but largely tell you if you have to buy 7 or 14 or 21 days prior to departure, have a Saturday stay, or are restricted to travel on certain days of the week like Tuesday, Wednesday, or Saturday (the lightest travel days for most routes).

If you meet those rules you need the specific flight you’re looking at to be available with inventory that matches the fare.

Airlines want to sell each seat for as much as possible but not have seats go out empty because then they get nothing for the seat.

Airlines don’t know exactly what seats will go empty a year out and consumers insisting on buying then are probably not that price sensitive. It is often the cruise crowd wanting to lock in their plans. Except for the highest of demand dates — the Superbowl, peak Spring Break in Florida — buying when schedules load is far too early.

Peak holidays sell out of cheap seats earlier largely because those flights do sell out.

Ways to Find Great Airfare Deals Over the Holidays

There’s no magic bullet day of week to book, but there are general rules for how far in advance to book. Do these things and you’ll get the best overall deal on your tickets.

• In general you should buy domestic flights 1 to 3 months out and international trips a little farther in advance, of course only if your plans are truly firm. The cheapest fares for holiday travel get booked early. Weekends aren’t really cheaper days to buy tickets and neither are Wednesdays at 1am.

  

• Know what tickets usually cost for your route. If prices are below that — buy. If prices are higher than usual you probably want to wait, especially if you’re still more than a month away from travel.

• Start considering purchasing when your plans are firm. Don’t purchase earlier because $200 (or higher) change fees will eat you alive. Don’t start later because of rising prices for close-in departures. Don’t stress about the deal you could have gotten. . Pounce when the deal is good enough.

  

• Comparison shop at Kayak.com or Hipmunk.com, sites that do the work of checking other airfare sites for you. If you really want to watch for sales, follow TheFlightDeal.com

• Look international. I’ve traveled internationally over Thanksgiving more often than I’ve visited family. Awards are often pretty easy to get, there are plenty of empty seats to and from the U.S. As I explained to a customs officer on return to the U.S. one time, it wasn’t any more miles to go to Asia than it would have been to visit my wife’s family on the West Coast. People fly over the holidays but it’s mostly visiting families domestically.

• Consider first class. As it is, airlines have reduced the difference between coach and first class tickets, and are selling more seats up front (versus giving them away as upgrades) as a result. During the holidays the spread between the two cabins can be even less, double so for international routes. That’s because there’s pretty much no business travel happening and business travelers are the ones who buy premium tickets on longer flights. So coach gets expensive (because cabins are full) but the big seats go for less (because companies aren’t buying them). If you’re going to travel anyway, it’s worth checking how much it costs to travel comfortably.

Much of the advice that’s key to getting a great deal comes down to baseball hall of famer Wee Willie Keeler, “Keep your eye clear, and hit ’em where they ain’t. Buy tickets before everyone else has filled up the plane. Go where other travelers aren’t, or in a class of service where they aren’t. Consider flying on an off day when fewer people want to travel (go home the day after Thanksgiving not the Sunday after for instance).