How Long is a Microblog?

Twitter originally had a character limit of 140, based on the limit of SMS messages of 160, with 20 reserved for the username, many years later it was increased to 280. Bluesky's limit is 300, on Mastodon it can differ server to server but the default is set to 500. So how long is a microblog post, and is the number of characters the only thing that counts? (this post, prior to this message, was 359 characters) Previous