Engagement Rate by Reach by Followers
Social MediaAlso: ER by Reach vs ER by Followers · Engagement Rate Calculation Methods
Quick definition
Engagement rate can be calculated two different ways. Engagement rate (ER) by reach divides engagements by the number of accounts who saw the post. ER by followers divides the same engagements by total follower count. The two numbers can differ significantly for the same post.
Run the same engagements figure divided by follower count instead of reach and compare the two results. A large gap between them usually points to reach problems, not content problems.
How it varies across Australia
Australian social accounts typically show a meaningfully higher engagement rate when measured by reach than when measured by followers, because reach is always equal to or smaller than follower count. The gap widens for accounts with large, inactive follower bases built through paid growth or old contests.
Compare social media performance across Australian industries →Two ways to calculate the same metric
Engagements divided by the number of unique accounts that saw the post. Measures how well the post performed with the people who actually saw it.
Always equal or higher than ER by followersEngagements divided by total follower count, regardless of how many followers saw the post. Common on agency reports because followers is easier to state publicly.
Always equal or lower than ER by reachWhat it actually means
Engagement rate answers a simple question: of the people who could have reacted to your post, how many did. The argument starts with who counts as "could have."
Engagement rate (ER) by reach uses the number of accounts who actually saw the post as the denominator. It's the more honest measure of content quality because it only judges the post against people who had a real chance to engage.
Engagement rate by followers uses total follower count instead. That number is stable, easy to find, and looks impressive in a pitch deck. It's also misleading for any account whose reach falls well short of its follower count, which is most accounts, most of the time, because algorithms don't show every post to every follower.
The gap between the two numbers tells you something useful on its own. A large gap usually means low organic reach relative to audience size, often from an inflated or disengaged follower base. This connects directly to impressions and reach as separate metrics, and to why click-through rate (CTR) and conversion rate matter more than either engagement figure once you're judging real business impact rather than vanity metrics.
Ask which denominator was used before you believe an engagement rate. The same post can look brilliant or mediocre depending on which one someone picked.
How to calculate it
ER by reach = Engagements divided by reach, multiplied by 100. ER by followers = Engagements divided by follower count, multiplied by 100
Worked example. A post gets 300 engagements, reaches 5,000 accounts, and the page has 20,000 followers. ER by reach = 300 divided by 5,000 = 6 percent. ER by followers = 300 divided by 20,000 = 1.5 percent. Same post, same engagements, a fourfold difference depending on which formula is used.
The Australian context
Australian brands with follower bases built through 2016-2020 era competitions or bought-follower campaigns often show the widest gap between the two engagement rate versions. Meta and TikTok algorithms in the Australian market show organic posts to a shrinking share of followers year on year, so ER by followers keeps drifting down even when content quality hasn't changed. Reporting only that number to a business owner without context makes the marketing look like it's failing when the real story is platform-driven reach decline across the whole industry.
Where people get this wrong
Related terms
Common questions
Which engagement rate formula should I use?
ER by reach for judging content quality, because it only counts people who actually saw the post. Keep ER by followers as a secondary number to track audience health over time, but don't use it alone to judge a single post's performance.
Why is my engagement rate by followers so much lower than my engagement rate by reach?
It usually means your organic reach is a small fraction of your total follower count, which is normal on most platforms today. A large gap points to algorithm-driven reach decline or an inflated follower base rather than a content problem.
Can I compare engagement rate across platforms?
Only if both platforms use the same formula and similar reach mechanics. Instagram, TikTok and LinkedIn all define reach and engagement slightly differently, so a raw comparison across platforms is unreliable even before you consider which denominator was used.
Does a high engagement rate mean the post drove business results?
Not necessarily. Engagement rate measures interaction, not outcome. A post can score well on either formula and still generate no clicks or sales. Check click-through rate and conversion rate before treating engagement rate as a proxy for revenue impact.
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About New Rebellion
New Rebellion is a marketing intelligence consultancy. We build tools, score Australian businesses on how their marketing actually performs, and publish Debrief every day. This dictionary is part of how we work in the open.
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