WordPress Estimated Read Time

estimate-read-time.php

<?php
/**
 * Estimates the reading time for a given piece of $content.
 *
 * @param string $content Content to calculate read time for.
 * @param int $wpm Estimated words per minute of reader.
 *
 * @returns	int $time Esimated reading time.
 */
function prefix_estimated_reading_time( $content = '', $wpm = 300 ) {
	$clean_content = strip_shortcodes( $content );
	$clean_content = strip_tags( $clean_content );
	$word_count = str_word_count( $clean_content );
	$time = ceil( $word_count / $wpm );
	return $time;
}

output.php

<div class="reading-time">
  <?php echo prefix_estimated_reading_time( get_the_content() ); ?> min read
</div>