Engaged Users: The number of unique people who clicked, liked, shared or commented on your Page's content.
Reach: The number of unique people who saw your Page's content.
Avg Post ER:
A single post’s ER: engaged users / reach
A single day’s ER: total engaged users for the day's posts / total reach for the day's posts
Avg Post ER: sum of single post ERs / number of posts in time period
Daily Post ER:
A single post’s ER: engaged users / reach
A single day’s ER: total engaged users for the day's posts / total reach for the day's posts
Daily Post ER: sum of single day ERs / number of days in time period
Avg Page ER:
A single day’s ER: (likes + comments + shares) / fans on the day / number of posts on the day
Avg Page ER: sum of single day ERs / number of posts in time period
Daily Page ER:
A single day’s ER: (likes + comments + shares) / fans on the day
Daily Page ER: sum of single day ERs / number of days in time period
Post ER by Reach:
Average engagement rate per post. It includes likes, comments, shares, clicks and reactions.