According to the data from the airfarewatchdog.com the best days fly are Tuesdays and Wednesdays.
Expedia’s data indicates that for long-haul flights, leaving on Thursday and returning on Monday costs around 20 percent less than leaving on Friday and returning on Saturday.For short-haul trips, Expedia’s lowest-fare groupings are Monday, Tuesday, and Wednesday both ways.
For more information visit https://www.airfarewatchdog.com/blog/22702034/the-cheapest-days-of-the-week-to-fly/?source=99961