Vocabulary Diversity (SpeechRater™ Dimension)

Vocabulary Diversity in TOEFL Speaking

What’s Inside?

Table of Contents

Vocabulary Diversity in TOEFL® Speaking refers to your ability to use a wide range of vocabulary words in your speech.

This means using a variety of different words to express your ideas and avoid repeating the same words over and over again.


A proficient speaker adept in vocabulary diversity communicates thoughts clearly and efficiently.

Mastery of a diverse range of vocabulary enhances one’s ability to articulate ideas effectively in the speaking assessment

What is Vocabulary Diversity in TOEFL® Speaking?​

Vocabulary Diversity (VDi) in TOEFL® Speaking is a SpeechRater™ indicator of your language use.

VDi is a measure of how varied your vocabulary is in terms of different forms of speech (e.g., nouns, adjectives, adverbs, etc.).

Stronger speakers tend to

  • Use a variety of vocabulary items in their speech.
  • Use different word forms accurately.

Your Vocabulary Diversity Score​

Your Vocabulary Diversity score is calculated based on the number of word types you use in your speech and the comparison of words used in your speech with responses receiving the maximum score.

Vocabulary Diversity is scored out of 100. Your score is indicated by the “You are here” line.

Tip: Learn more about how to read My Speaking Score charts, including the Impact score and what the coloured bars mean, in our knowledge base.

Why You Should Care

  • Those who score 26+ on TOEFL Speaking have an average VDi score of 81.49.
  • VDi is one of the mild predictors of your overall TOEFL speaking score.


Increase Your Score

Make sure you use a variety of word forms in your speech and use them accurately.

On My Speaking Score, remember to check your transcript and the distribution of the word forms you used in your speech.

Remember, Vocabulary Diversity is a measure of your language use. It does not have a high impact on your speaking score, but a low Vocabulary Diversity score can decrease your overall SpeechRater score.

Frequently Asked Questions

How Is The Vocabulary Diversity Score Actually Calculated?

The Vocabulary Diversity score is calculated through a sophisticated algorithm used by the SpeechRater™ system. This algorithm analyzes your speech for the variety of word types used, including nouns, verbs, adjectives, and adverbs. It then compares your usage of these word types against a database of high-scoring responses. Factors such as the uniqueness of the words used, the range of different word forms, and the appropriateness of word choice in context are all considered. Each aspect contributes to a composite score out of 100, aiming to reflect your ability to use a diverse vocabulary effectively in your speech.

What Specific Strategies Can Test-Takers Employ To Improve Their Vocabulary Diversity In TOEFL Speaking?

Improving your Vocabulary Diversity involves a multi-faceted approach. Here are some strategies that can help:

  • Read Widely: Engage with a variety of English texts, including books, articles, and reports across different genres and subjects. This will expose you to a broad range of vocabulary.
  • Practice Synonyms: For words you commonly use, learn synonyms that can convey similar meanings. This practice will help you avoid repetition in your speech.
  • Use Language Learning Apps: Apps designed for language learning can offer personalized vocabulary exercises, making it easier to learn and practice new words regularly.
  • Engage in Active Speaking Practice: Regularly practice speaking on a variety of topics. Try to incorporate new words into your speech deliberately. Recording yourself can help you identify patterns and areas for improvement.
  • Seek Feedback: Engage with language tutors or peers who can provide constructive feedback on your vocabulary usage and suggest areas for expansion.

How Does Vocabulary Diversity Compare In Importance To Other Factors In The TOEFL Speaking Section?

While Vocabulary Diversity is an important aspect of the TOEFL Speaking section, it is one of several dimensions evaluated by the SpeechRater™ system. Other critical factors include grammatical accuracy, pronunciation, fluency, and the overall coherence of your responses. Although Vocabulary Diversity is identified as a “mild predictor” of your overall speaking score, it is essential to understand that a balanced approach is key. Excelling in Vocabulary Diversity while neglecting other aspects such as fluency or grammatical accuracy may not lead to a high overall score. Therefore, it’s crucial to focus on improving all areas of your speaking skills for the best possible outcome on the TOEFL Speaking section.

ChatGPT & TOEFL® Speaking Prep

The AI-powered virtual assistant ChatGPT is an excellent resource for TOEFL Speaking practice. With carefully written instructions, it delivers beautiful responses to your inputs. Though you may need to ask a question more than once, the process of coaxing out various responses from ChatGPT is not only fun but also informative.

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