Follower counts are easy to inflate. Engagement rate shows how many of those followers actually react. Enter the averages from the last 10 to 12 posts.
The formula
(average likes + average comments) / followers x 100. This is the by-followers method, the one most brands and platforms quote.
What counts as good?
As a rule of thumb: under 1% is low, 1% to 3.5% is average, 3.5% to 6% is high, and above 6% is very high. Small accounts usually score higher than large ones, so compare creators of a similar size.
Questions
Which posts should I average?
The last 10 to 12, leaving out any single viral post. One outlier makes the rate look better than a sponsor will see.
Can engagement be faked?
Yes. Bought likes and comment pods both raise the number. Read the comments: generic one-word replies from unrelated accounts are the usual sign.