Surprise! There is. Forty-seven days before takeoff is when domestic plane tickets are at their absolute cheapest, according to a study of 2014 flight data from online travel agency CheapAir.
The number is seven days sooner than last year’s estimate of 54 days before takeoff — it’s based on 1.5 billion fares from 2014, while last year’s study analyzed data from 2013.
Flight prices fluctuate from the day they’re released all the way up until takeoff. The CheapAir study found that flights purchased on their “best price” day (usually about 47 days before takeoff) were an average of $201 cheaper than flights purchased on their “worst price” day, which usually falls within seven days of the trip.
This means that the day you book your ticket is very important, and you should aim for 47 days before your trip. The day of the week that you book won’t affect prices much, but the day you fly probably will — aim for a Tuesday or Wednesday. (Some, however, would disagree with this rule.) As you might guess, this doesn’t necessarily apply to holiday flights, which have rules of their own.