The cheapest days to fly are tuesday and wednesday according to Cheapest days to fly. Why you may ask? it's because they are the days least flown on. I bet you were planning on flying on a Friday or a Monday, weren't you? Well those are probably the most expensive days to fly on since everybody wants to fly on those days!
Those are the most popular days to fly on because many people end their work week on a friday and start it on a Monday, that way if they fly on those two days, they can depart on Friday and return on Monday. It may be easier for your schedule to fly on those days but it definitely won't be easier on your wallet.
I believe the single cheapest day to fly is on a wednesday because even less people fly on Wednesday than on Tuesday! This is probably because Wednesday is right in the middle of the week and people usually don't like to throw off their schedule midweek to travel. It's just not convenient!
If you plan on saving money flying, for sure try to get a flight scheduled for one of the two cheapest days to fly. If you're desperate, Wednesday is the day to go. Just remember, like I said in my last post, flight prices are constantly changing so any given Wednesday or Tuesday has the possibility to be more expensive than a Friday in instances such as when there's a four day weekend coming up ahead!