The three formulas
All engagement rate formulas share the same skeleton: total interactions ÷ a base × 100. The bases differ:
- By followers — ER = (likes + comments + shares + saves) ÷ followers × 100. The default for comparing accounts. Standard on Instagram, TikTok and Facebook.
- By reach — ER = total engagements ÷ reach × 100. The fair basis when a post travelled beyond your follower base (viral Reels, TikToks).
- By impressions — ER = total engagements ÷ impressions × 100. The industry standard on LinkedIn and X, where algorithmic feeds make impressions the honest denominator.
Worked example: Instagram (by followers)
Account: 12,400 followers. Latest carousel: 480 likes, 32 comments, 18 saves, 9 shares. Total interactions = 539. ER = 539 ÷ 12,400 × 100 = 4.35% — excellent for the platform (average ≈ 0.5%). Verify it: Instagram engagement rate calculator.
Worked example: TikTok (by followers vs by views)
Account: 45,000 followers. Video: 3,200 likes, 210 comments, 140 shares, 380 saves = 3,930 interactions. By followers: 3,930 ÷ 45,000 × 100 = 8.73%.
The same video got 130,000 views. By views: 3,930 ÷ 130,000 × 100 = 3.02% — still excellent per view. The by-follower number flatters breakout posts; quote both, or quote by-views for the viral case. TikTok calculator.
Worked example: LinkedIn (by impressions)
Post analytics: 18,000 impressions, 240 reactions, 45 comments, 12 reposts = 297 interactions. ER = 297 ÷ 18,000 × 100 = 1.65% — good (average ≈ 2% for healthy posts; above 5% is viral by LinkedIn standards). LinkedIn calculator.
Which basis should you use?
- Comparing accounts → by followers (what brands quote).
- Judging a single breakout post → by reach/views.
- LinkedIn or X → always by impressions (shown on every post).
- YouTube → per view; per-subscriber numbers only make sense between similar-size channels.
Calculation mistakes that distort your numbers
- Averaging ratios instead of aggregating: averaging each post's ER with different bases mixes units. Aggregate interactions and bases across the window, then divide once.
- Ignoring saves and bookmarks: they are the heaviest quality signals on Instagram, TikTok and X. Leaving them out understates real engagement.
- Using lifetime followers for a single post: follower counts drift daily; for single-post analysis, by-reach is cleaner than by-follower.
- Mixing bases in one comparison: never put a by-follower number next to a per-impression number without labelling them.
Frequently asked questions
What counts as an engagement?
Likes/reactions, comments, shares/reposts and saves/bookmarks. Clicks-through and profile visits are useful but are not counted in the standard ER formulas.
How do I calculate ER across several posts?
Sum all interactions and divide by the sum of the base (followers is constant; reach or impressions should be summed across posts), then × 100. Or use each platform's analytics export.
Should I divide by followers at post time or today?
For trend tracking, today's follower count is fine for by-follower ER. For judging a specific post, by-reach avoids the drift entirely.
Is there a free calculator?
Yes — the EngageCalc calculator runs all three bases instantly in your browser, with rating bands per platform.