Engagement calculation is different for each platform. Below is the breakdown.
Twitter: Retweets + Likes
Instagram Business: Likes + Comments
Update: Starting January 19, 2024, the revised formula for computing "Engagements" on authenticated Instagram profiles involves aggregating Likes, Shares, Comments, and Saves. The tracking of Shares will commence from the specified implementation date.
Due to limitations in Meta's API, the ability to track the number of Shares is applicable to most countries, excluding Japan and European countries.
Facebook: Likes + Comments + Shares
TikTok: Likes, Comments and Shares
YouTube: Likes + Comments
Note: Any YouTube posts collected prior to November 10th, 2021 will also include dislikes within the engagement metric.