It is clear that the optimal number of hashtags is exactly 30 if you want to get a lot of likes on posts. The average number of likes per follower increases steadily with the number of hashtags used. The results are not only visible to the naked eye, they are also statistically detectable: There is a significant correlation between hashtags and likes per follower.

Interestingly, using more than 30 hashtags is not at all advisable. Instagram does not seem to ignore the excess of hashtags but actually punishes it. Each additional hashtag seems to cost quite a bit of interaction and finally it would result in a shadow ban.

Should you always use 30 hashtags?

Definitely yes, if you aim to get as many likes as possible. Hashtags are baits for both bots and real users. However, if you do not want to optimize your posts for likes but for reach, the story is a bit different.

In a second analysis of 1.5 million posts, we looked at how much reach per follower they received, and related that to the number of hashtags. This relationship is also statistically significant and detectable. However, the findings are not quite as clear.

While the reach increases significantly with the use of hashtags, with more than 24 hashtags, it seems to be declining again. A polynomial approximation yields an optimum of 20 hashtags. Unlike with likes, it does not seem optimal to maximize reach by using 30 hashtags.