Free Word Variety & Perplexity Checker

Check how repetitive your vocabulary is with a free perplexity and Shannon entropy analysis. Spot overused words, measure lexical diversity, and improve your writing — no signup needed.

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Key Takeaways: AI Perplexity & Entropy

Perplexity measures how 'surprised' an AI model is by your word choices. High perplexity means your vocabulary is diverse and unpredictable.
AI models generate text with low perplexity because they mathematically pick the most probable next word.
Use this free calculator to measure your text's Shannon entropy and perplexity score.
To increase your score and lower AI detection risk, introduce less common synonyms and vary your sentence structures.

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From the Conch team

Why ChatGPT uses the same 200 words to write everything

Language models are probability machines. When generating the next word, they always pick the safest, most expected choice — which is usually one of the same recurring words: "significant", "important", "demonstrate", "challenge", "provide". The result is prose that is grammatically flawless but rhythmically dead. Shannon entropy, the measure this tool uses, was originally developed to measure information in telecommunications signals. Applied to writing, it captures how "surprising" your word choices are. A low entropy score means your writing is highly predictable — the same words keep appearing. Human writers are naturally more erratic, jumping between concrete and abstract, technical and colloquial, precise and poetic. This tool finds where you are stuck in vocabulary loops and shows you which specific words to swap.

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Conch Tip: The 'Top Repeated Words' list is your shortcut. Find the top 3 non-stopwords and replace 50% of their occurrences with specific synonyms. That single change usually adds 8–12 entropy points.

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Frequently Asked Questions

What is perplexity in writing analysis?

Perplexity measures how predictable or repetitive your text is. In this tool, it's calculated as a browser-side heuristic based on word diversity (Shannon entropy) — not a language model score. Repetitive word patterns produce a lower perplexity score, while varied vocabulary produces a higher one. Most human writers score above 80; AI-generated text often scores below 45.

What is Shannon entropy and how does it apply to writing?

Shannon entropy is an information theory measure of 'surprise' or unpredictability in a sequence. In writing analysis, it measures how diverse and unpredictable your word choices are. A text where the same 20 words repeat constantly has low entropy. A text with rich, varied vocabulary has high entropy. More varied writing tends toward higher entropy — and generally sounds more natural and engaging.

What is a good vocabulary diversity score?

In this tool's scoring system, a perplexity above 80 indicates good vocabulary variety — typical of experienced human writers. Scores between 45 and 80 are moderate, suggesting some repetition. Scores below 45 indicate significant word repetition, which can make writing feel formulaic or AI-generated. For academic essays, aim for a score above 70.

How can I improve a low perplexity score?

To improve your score: (1) Identify the most repeated words using the 'Top Repeated Words' list in the results. (2) Use synonyms for the most overused terms — a thesaurus or Conch Rewrite Mode can help. (3) Vary your sentence structures so different types of words appear. (4) Replace generic terms ('good', 'bad', 'things', 'stuff') with specific, concrete vocabulary.

Does word repetition affect AI detection?

Yes. Low vocabulary diversity is one of the signals AI detectors measure. AI language models like ChatGPT tend to favour certain 'safe' vocabulary — reusing the same connecting words, transition phrases, and generic nouns repeatedly. Human writers typically use more varied, idiosyncratic word choices. Improving your vocabulary diversity can help reduce AI detection scores.

What does the sentence colour coding mean?

Each sentence in the 'Sentence Analysis' panel is highlighted in one of three colours: green (Varied) means that sentence has strong vocabulary diversity relative to your overall text; yellow (Mixed) means moderate diversity; red (Uniform) means that sentence uses repetitive vocabulary and should be a priority for improvement. Click any sentence to see its individual perplexity score.

Does the tool send my text to a server?

No. All calculations — entropy, perplexity, word frequency — run entirely in your browser using JavaScript. Your text is never transmitted to any server. You can verify this by opening your browser's Developer Tools (F12) and checking the Network tab while the analysis runs. You'll see zero outbound requests.

How is this different from a plagiarism checker?

Plagiarism checkers compare your text against a database of existing documents to find copied content. This tool does something completely different: it measures the internal diversity of your own vocabulary and writing style. It doesn't compare against any external database and doesn't detect copying — it helps you write with richer, more varied language.

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