Two formulas, two questions
By followers answers "how much of my audience reacts?" — useful for comparing accounts of similar size. By views answers "of the people who actually saw this, how many reacted?" — the fairer measure on TikTok and Reels, where most views come from non-followers.
Reading the number
There is no universal "good" rate: it falls as accounts grow, and differs by platform and format. Compare a post against your own previous posts rather than against a benchmark from a blog. One practical note: a follower count that grows far faster than interactions drags the by-followers rate down — which is why pacing growth, and pairing followers with engagement on the posts themselves, matters.
Questions
Which engagement rate do brands look at?
Usually engagement by followers for a quick screen, then engagement by reach or views on recent posts. Give both.
Should saves and shares count?
Yes. They are the strongest intent signals on Instagram and TikTok, and leaving them out understates how a post performed.