Reading Rate refers only to the number of words that a child reads per minute. This is one aspect of fluency that helps determine whether a child's reading behaviors are on grade level.
"Recommended reading rates, or words read per minute, for grades one through six is a way to determine whether (students are able) to recognize words automatically. The comparison can also be used to determine whether a student's reading rate is near the grade level standard. For example, a beginning third grade student with a reading rate of 110 WPM can be considered on level. However, a third grade student with a reading rate of 60 WPM is recognizing words at a rate similar to a first grader and will likely need additional instructional support to increase his or her reading rate." (readinga-z.com)
Click here for a chart that shows end of grade level reading rate expectations.