Giustino Borzacchiello

This plugin will show stats about your posts after your content.
Currently it shows:
<ul>
<li>Word count</li>
<li>Characters count</li>
<li>Reading time</li>
<li>Speaking time</li>
</ul>

Postats

This plugin gives some statistics about your posts (word count, etc.)

brianmcculloh

A very unobtrusive and light-weight reading progress bar indicator showing the user how far scrolled through the current post or page they are. You can control placement and color of the progress bar, and you can choose whether it includes just the main content or also the comments.
The progress bar only displays once the user begins scrolling the page so it is as unobtrusive as possible. Once the user stops scrolling or scrolls down past the content the progress bar subtly mutes until it is needed again.
There is also a reading time commitment feature that you can separately enable. Control the placement (above or below title, or above content), style, and whether it displays on posts and/or pages. Uses 200wpm as the metric for average reading time.
You can also place the time commitment label anywhere you want via the [wtr-time] shortcode.

Worth The Read

Looks very promising, but on my site, nothing was added.

Absolutely does not anything :(

An adjustable progress meter showing how much of the post/page the user has scrolled through, and a read time commitment label near the post titles.

Postats vs Worth The Read