When you read an academic paper, it often feels heavier and denser than a casual blog post — even if both cover the same topic. One reason for this is lexical density, a measure of how much of a text is made up of content words versus grammatical filler. Understanding lexical density can help writers calibrate their style, and it can tell linguists a lot about how language is used across different registers.
What Is Lexical Density?
Lexical density is the proportion of lexical words (also called content words) to the total number of words in a text. Lexical words carry semantic meaning — they are the words that describe the world: nouns, main verbs, adjectives, and adverbs. Everything else — articles, prepositions, conjunctions, pronouns, auxiliary verbs — are function words, which provide grammatical structure but add little to the information load.
A text with high lexical density packs more information into fewer words. A text with low lexical density is more conversational and easier to process, because more of its words are grammatical anchors rather than information carriers.
The Lexical Density Formula
The most widely used formula was proposed by linguist Ure (1971):
For example, in the sentence "The quick brown fox jumps over the lazy dog":
- Total words: 9
- Lexical words: quick, brown, fox, jumps, lazy, dog = 6
- Function words: The, over, the = 3
- Lexical Density: (6 ÷ 9) × 100 = 66.7%
Content Words vs. Function Words
| Content Words (counted) | Function Words (excluded) |
|---|---|
| Nouns (dog, table, analysis) | Articles (a, an, the) |
| Main verbs (run, calculate, write) | Prepositions (in, on, at, over) |
| Adjectives (quick, dense, complex) | Conjunctions (and, but, because) |
| Adverbs (quickly, clearly, often) | Pronouns (he, she, they, it) |
| Auxiliary verbs (is, are, have, will) |
What Is a Good Lexical Density Score?
Lexical density varies significantly by register — the type and context of language use. Here are typical ranges:
- Spoken conversation: 40–50% — Lower density because spoken language relies on shared context and uses more pronouns and filler words.
- General-audience writing: 45–60% — Balanced information density without being overwhelming.
- Academic and technical texts: 60–70% — High density because technical writing packs many concepts into formal prose.
- Legal documents: 65–75% — Extremely dense, optimized for precision over readability.
How TextAnalyzer Calculates Lexical Density
TextAnalyzer uses a curated list of English function words — articles, prepositions, conjunctions, pronouns, and common auxiliary verbs — and subtracts them from the total word count to arrive at the number of lexical words. The density is then computed as the ratio of lexical words to total words, expressed as a percentage.
You can configure the stop word list in TextAnalyzer's settings, which allows you to adapt the calculation for different languages or specialized domains.
Why Lexical Density Matters
Lexical density has practical applications across several fields:
- Writing and editing: Identifying overly dense passages and simplifying them for a general audience.
- Language teaching: Measuring text difficulty to match learner levels.
- Corpus linguistics: Comparing language use across genres, time periods, or speakers.
- Content strategy: Making sure marketing copy is approachable without being empty.
How to Adjust Your Lexical Density
If your text is too dense, try breaking long noun phrases into shorter clauses, using active voice (which introduces more grammatical structure), and defining technical terms rather than stacking them. If your writing is too sparse, reduce hedging language, cut filler phrases, and favour precise nouns over vague pronouns.
