Enter the total number of words and the total number of utterances into the calculator to determine the Mean Length of Utterance (MLU); this calculator can also evaluate any of the variables given the others are known.

Mlu (Mean Length Of Utterance) Formula

The following formula is used to calculate the Mean Length of Utterance (MLU):

MLU = (TW / UW)

Variables:

  • MLU is the Mean Length of Utterance
  • TW is the total number of words
  • UW is the total number of utterances

To calculate the Mean Length of Utterance, divide the total number of words by the total number of utterances.

What is a Mlu (Mean Length Of Utterance)?

Mean Length of Utterance (MLU) is a measure used in the field of language development to quantify the linguistic progress of children. It is calculated by collecting a sample of a child’s spontaneous speech, counting the total number of morphemes (the smallest meaningful units of language), and dividing by the total number of utterances (independent clauses). The resulting number represents the average length of the child’s utterances, providing an indication of their syntactic complexity and overall language proficiency. MLU is often used in research and clinical settings to assess language development and identify potential language impairments. It is considered a reliable and valid measure of early language development, particularly for children between the ages of 20 months and 4 years.

How to Calculate Mlu (Mean Length Of Utterance)?

The following steps outline how to calculate the Mean Length of Utterance (MLU).


  1. First, gather a sample of spoken or written language.
  2. Next, count the total number of morphemes in the sample.
  3. Next, count the total number of utterances in the sample.
  4. Finally, calculate the Mean Length of Utterance using the formula MLU = Total number of morphemes / Total number of utterances.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem:

Use the following variables as an example problem to test your knowledge.

Total number of morphemes = 50

Total number of utterances = 10