Have vacation plans for 2018 or 2019?  Now is the time to start thinking about getting the most affordable air fares available. Plane ticket prices fluctuate, and when you purchase your ticket can mean a difference of literally hundreds of dollars, depending on where you’re traveling to.

CheapAir.com's 2018 Airfare study looked at 917 million different flights listed on its site to determine where the perfect time to buy is.

So, how far in advance should you buy? Here are three quick take-aways from the CheapAir.com study...

1- the best window of time to purchase a ticket in 2017 was 70 days in advance, but it really depends on the season when you plan to travel. In winter you want to try for 62 days in advance, spring 90 days in advance, summer 47 days in advance, and fall 69 days in advance.

2- CheapAir.com says that’s not really true that there’s a best day of the week to buy. Airfare during the week traditionally doesn’t fluctuate more than $2 from day to day, so you’re fine buying a ticket any day you want.

3- When it comes to when you fly, there is a difference. The cheapest days to fly are Tuesday and Wednesday, while Sunday is the most expensive.

Source: CheapAir. com