Lexical Density: How Much Information Is Your Prose Carrying?

Every sentence you write is made of two kinds of words. Content words carry meaning: nouns, verbs, adjectives, adverbs. Function words glue them together: the, a, of, is, that, and the rest of the small connective machinery. Lexical density is just the ratio of one to the other. Divide content words by total words. The number tells you how much weight your sentences are actually pulling.

Prose with high density packs information. Prose with low density has more air in it. Neither is correct. But knowing where yours is sitting, and why, is one of the best diagnostic tools you can run on a draft.

What high and low density look like

Journalism, technical writing, and most commercial nonfiction run high on density, often above 0.55. The writer is trying to fit maximum signal into minimum space. The reader is scanning for information. Every content word earns its place because the economy of the form demands it.

Casual speech runs low, around 0.40. So does prose that deliberately mimics the rhythm of talking. Dialogue between characters will almost always score below the narrative surrounding it, because people do not speak in content words. We speak in hedges, fillers, and connecting phrases. If your dialogue is scoring as dense as your prose, something is off.

Why low density creeps in

The most common reason for low density is not dialogue. It is filler. Certain phrases do almost nothing but add function words: it is worth noting that, at the end of the day, in order to, for the most part. These phrases feel polite. They read like throat-clearing. Each one dilutes the content-word ratio without adding meaning.

The second reason is weak noun-verb stacks. Made a decision has one content word doing the real work and two helpers. Decided does the same job with one word. Came to the realization that has three content words for what realized accomplishes alone. Once you start seeing these stacks, you see them everywhere in your own drafts.

How to raise density on purpose

Cut filler phrases. Most of them can be deleted without the meaning changing. If a phrase signals to the reader that you are about to say something, just say the thing. The reader was already paying attention.

Replace noun-verb stacks with single strong verbs. Made a decision becomes decided. Conducted an investigation becomes investigated. Was in possession of becomes had. This one pattern alone will often raise density by three or four points.

Watch for stacked prepositions. A sentence that reads the door at the end of the hall of the house is five function words and two content words. Usually it wants to be the door at the end of the hall, or just the hall door.

Why this metric earned its place

I almost did not include lexical density in the first version of the engine. I thought writers would find the term too academic. Then I started using it on my own drafts. The score consistently flagged the paragraphs I would later cut for being slack, before I had decided to cut them. After enough of those, I shipped the metric.

A practice loop for density

1. Paste two hundred words of your writing into Prose Grade and note the lexical density.
2. Underline every phrase that could be replaced with a single word. Come to an agreement to agree, and so on.
3. Delete every filler phrase that is only signaling you are about to make a point.
4. Look at your subordinate clauses. If one starts with that is, which is, or who is, ask whether you can cut the clause marker.
5. Regrade the passage. Expect a noticeable jump.

When low density is correct

Dialogue, as mentioned, naturally runs low. If you compress dialogue the way you compress exposition, it stops sounding like speech. A character who speaks in dense content-word bursts reads as stiff.

Some literary prose also runs low on purpose. Sentences that drift, circle, or accumulate often do so with function words carrying the rhythm. Virginia Woolf, for example, writes long sentences threaded with small words. The density score misses what those sentences are doing. The score is measuring efficiency, not music.

Personal essays occupy the middle ground. They lean on conversational rhythm where the prose is thinking out loud, and tighten into density where the idea has to land. The best essays vary both within the same piece.

The right question

Lexical density is not a virtue signal. The goal is not to hit 0.60 on every page. The goal is to ask, every time you write: is this sentence doing work, or is it filling space? High density is the symptom of a draft that already answered that question.

Run your next draft through Prose Grade and see where your density sits. If the score surprises you, it probably has something to tell you about where the prose is coasting.