According to FareCompare, Tuesday really is the best day to buy airfare. Specifically, you want to shop at 3 p.m. eastern time on Tuesday afternoons, because that’s when the prices airlines have adjusted to match sales published on Monday afternoon hit the system.

You should also buy sometimes between 3 1/2 months and 2 weeks prior to departure.

Finally, according to the article, Tuesday, Wednesday and Saturday are the cheapest days to fly.