All posts engagement rate = (posts|reactions + post|comments + post|shares) / post|impressions * 100;
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All posts engagement rate = (posts|reactions + post|comments + post|shares + clicks) / post|impressions * 100;

Engagement rate = engagement / followers * 100;

Public engagement rate = engagements / impressions *100

Average Engagement = (clicks + (total_engagements - clicks)) / impressions * 100
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Engagement rate = (paid|clicks + free|clicks) / total impressions * 100
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