First, keep in mind that most Facebook users see your content in their
own news feeds – not on your page. Facebook sorts each individual news
feed according to each user's demonstrated preferences, but to a large
extent the news feed shows posts in chronological order. The posts on
top are most likely to be be read, while the ones on bottom are often
missed entirely. Most Facebook users read only a small percentage of
what is available in their own news feeds. Therefore, posting at the
time of day when there are the most users maximizes the reach of an
individual post.
As you might imagine, Facebook's lowest point is 3AM. The audience grows
rapidly from 6am to 9am. The audience grows steadily from 9am, peaking
at 1pm. From there, the audience troughs slightly. At 3pm, the audience
starts growing again, reaching a peak at about 5pm to 6pm. Consistently,
the greatest Facebook audience is at 9pm. The 9pm audience is 20% to
30% greater than the lunchtime audience and almost double the
breakfast-time audience.
You might glean from this that the best time to post is 9pm. If you have
a small fan base, this may work to your advantage, but for more
established pages, 9pm is not optimal. The problem is that the Facebook
audience drops off rapidly after 9pm. A Facebook post is “new” in news
feeds for about three hours after it is posted or shared. The greatest
three-hour block, by far, is from 6pm to 9pm. For maximum reach, the
best time to post is about 6pm.
This does not mean that every post should be at 6pm. Every user has
their own reading habits. Some read on their lunch breaks, some at
breakfast, some after the rest of the family has gone to bed. By varying
your post times on occasion, you maximize the total reach of your page.
By posting at 6pm more often than not, you maximize the reach of each
post.