Mean Length of Utterance Calculator

The Mean Length of Utterance (MLU) is a measure used in language development research to assess a child's linguistic competence. It calculates the average number of morphemes (word parts) in all of a child's utterances during a specific period.

Input Parameters

Calculation Results

Calculation Formula

MLU = Total Number of Morphemes / Total Number of Utterances

Where:
- MLU: Mean Length of Utterance
- Total Number of Morphemes: The sum of all morphemes counted in all utterances
- Total Number of Utterances: The total number of utterances recorded

Result

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The MLU score indicates the child's linguistic development level

Developmental Guidelines

  • MLU of 1.0-1.5: Infancy (around 12-18 months)
  • MLU of 2.0-2.5: Early Toddlerhood (around 18-24 months)
  • MLU of 3.0-3.5: Late Toddlerhood (around 24-30 months)
  • MLU of 4.0-4.5: Early Preschool (around 30-36 months)
  • MLU of 5.0-5.5: Preschool (around 3-4 years)
  • MLU of 6.0+: School Age (around 4+ years)

Mean Length of Utterance Calculator Usage Guide

Learn how to use the Mean Length of Utterance Calculator to assess language development

How to Use the Calculator

  1. Count the total number of utterances your child made during a specific observation period (typically 5-10 minutes).
  2. For each utterance, count all morphemes (word parts) including verbs, nouns, adjectives, adverbs, prefixes, suffixes, etc. For example, "runnin'" has two morphemes: "run" and "-in'."
  3. Enter the total number of utterances in the "Total Number of Utterances" field.
  4. Enter the total number of morphemes in the "Total Number of Morphemes" field.
  5. Click the "Calculate" button to determine the MLU score.

Understanding the Results

The MLU score provides a standardized measure of language development. A higher MLU indicates more complex language use. The calculator also includes developmental guidelines to help interpret the score in the context of typical language development milestones.

Important Considerations

  • MLU should be calculated consistently using the same observation period for accurate tracking of development.
  • For young children, observe and record their spontaneous speech rather than asking them to answer questions.
  • Remember that MLU is just one measure of language development and should be considered alongside other developmental indicators.
  • Individual variations exist in language development - use MLU scores as guidelines rather than strict milestones.