Add a Time to Read To Your WordPress Posts

functions.php

<?php
function time_to_read( $content = false ) {

    if ( is_single () ) {

        // If content has not been passed in (via the filter), fetch it

        if ( !$content ) { $content = get_the_content(); $add = false; } else { $add = true; }

        // Get the cache, if the content was not provided and this is not a preview

        $cache = false;
        if ( !$add && !is_preview() ) { $cache = get_transient( 'time_to_read_' . get_the_id() ); }

        // If cache was found, see if the post has updated. If so, trash it

        if ( $cache ) { if ( isset( $cache[ 'updated' ] ) && $cache[ 'updated'] != get_the_modified_date() ) { $cache = false; } }

        // If there is a cache, use it!

        if ( $cache ) {

            $content = $cache[ 'content'];

        } else {

            // Generate output

            $time = str_word_count( strip_tags( $content ) ) / 300;
            if ( $time == 0 ) { $time = 0.1; } // If there is no content, report < 1 minute
            $rounded = ceil( $time );
            $output = 'Time to read: ' . ( $time<1?'<':'' ) . $rounded . ' minute' . ( $rounded>1?'s':'' );
            $generated = 'Code generated';

            if ( $add ) { $content = $output . $content; } else { $content = $output; }

            // Save cache, if content was not provided and this is not a preview

            if ( !$add && !is_preview() ) {
                $cache[ 'content' ] = $content;
                $cache[ 'updated '] = get_the_modified_date();
                set_transient( 'time_to_read_' . get_the_id(), $cache );;
            }

        }

    }

    return $content;
}
?>

Add this to your functions.php code and then following the instructions on the blog post below on how to integrate this onto your site - the end result is a lovely 'Time to Read' added to each post.

https://artiss.blog/2017/02/add-a-time-to-read-to-your-wordpress-posts/