Plain Prose

Plain prose: understood in one pass

The bar: the reader gets it the first time, at reading speed, without going back to the start of the sentence. Many of your readers do not read English as a first language, and none of them owe you a second pass.

A sentence a reader has to parse twice is a defect. The writer saved a minute and charged it to every reader.

Plain does not mean shorter, and never means vaguer. A good rewrite is often longer than the original and says strictly more. Simplify the sentence, never the content.

The rules

Each rule is a test you can apply to a sentence without knowing the subject matter. The numbers come from published standards and studies — see the last section.

1. One idea per sentence. Cap a sentence that tells someone to do something at 20 words, and a sentence that describes something at 25. One topic per paragraph, at most six sentences.
2. Keep words close to the words they depend on. Reading cost comes from the distance between a word and the word it belongs to, not from length by itself. Keep the subject next to its verb, the verb next to its object, the modifier next to what it modifies. Never split a subject from its verb with a clause. A long, straight sentence reads easily; a short, tangled one does not.
3. Start with what the reader already knows. End on the new point. The end of a sentence is where the reader puts the emphasis, so the news belongs there — as the main clause. A point delivered in a trailing ..., which is what ... sits in the weakest position in the sentence. Cut the clause and make it the next sentence.
4. Budget one unfamiliar term per 50 words. A reader needs to know about 98 percent of the words to follow a text without help. That is one new term per two or three lines. Past that the text becomes a wall, whatever its sentence length.
5. Delete your team's private vocabulary. An invented word for a data layout, an in-house abbreviation, a metaphor left over from the design discussion — the reader has none of it. Write what the thing is. Defining the term in place does not repair the damage. An unfamiliar term slows the reader down and pushes them to give up, on top of whatever they fail to understand. Keep a term only when it is the field's shared name and no ordinary words replace it.
6. No noun stack longer than three words. Four or more nouns in a row is a compressed sentence. Unpack it into words with a verb in them.
7. Name the actor and use the active voice. "The platform team picks the date" beats "a date will be picked". Passive is for when nobody knows the actor.
8. Take the short word. use not utilize, so not thereby, lets not is what enables, before not prior to, about not with respect to. The long word buys no credibility — readers rate hard-to-read writing as coming from a less able author.
9. Say what the text is for in the first two sentences. In a message to a person, that means the ask and who owns it.
10. Keep every fact. Plain is not vague. Every number, caveat and condition in the original survives the rewrite.

Examples

The subject matter in these is irrelevant, and deliberately different in each. What transfers is the move, not the words.

A trailing clause and a noun stack (rule 3, rule 6):

before: The rollout is paused because the canary error budget consumption rate
        exceeded the threshold set for the deploy freeze window, which is why
        nothing shipped today.
after:  The canary used up its error budget too fast, so the rollout paused.
        Nothing shipped today.

Private vocabulary (rule 5), plus one idea per sentence (rule 1):

before: The fanout path now resolves through the slot table instead of walking
        the shard ring, so tail latency drops.
after:  A write goes to several replicas. The code used to check the shards one
        by one; now it looks each replica up in a table. The slowest writes get
        faster.

A buried actor and a nominalization (rule 7, rule 8):

before: It was determined that a decision regarding the migration timeline will
        be required from the platform team prior to the freeze.
after:  The platform team needs to pick a migration date. Please decide before
        the freeze starts on Friday.

In all three the facts survive and the terms that name real, shared things stay (canary, error budget, replica, shard, freeze). What goes is the invented naming, the stacked nouns, the trailing point, and the missing actor.

Rewriting text you did not write

Keep every fact, every number, every caveat. A rewrite that reads well and means something else is worse than the tangled original. Where you cannot tell what a sentence means, ask the author — do not guess, and do not quietly drop the sentence.

The check

Read the finished text once, at normal speed. Mark every sentence you went back into. Those are the ones to fix — usually by moving a word closer to what it depends on, or by cutting a trailing clause loose.

Do not use a readability score as the gate. Those formulas count word length and sentence length, and nothing else. They rate nonsense as highly readable, and they move several grades if you only add full stops. They cannot see rule 2, rule 4, or rule 5.

Two things this skill is not

• Not voice. Tone, warmth, greeting, how you sound — a voice or house-style skill owns that, and it outranks this one on wording wherever the two disagree.
• Not dumbing down. No glossary, no summary section nobody asked for, no explaining what the reader already knows. The reader is not slow. They are busy, and they may be reading in their third language.

Where the numbers come from

• 20/25 words per sentence, one topic per paragraph, six sentences per paragraph, three-word noun clusters, active voice, one instruction per sentence: ASD-STE100 Simplified Technical English, the controlled-language standard for aerospace documentation read worldwide by non-native speakers.
• Distance, not length, drives difficulty: Gibson's dependency locality theory, and Temperley's finding that written English already minimizes dependency length.
• Known information first, new point at the end: Gopen and Swan, The Science of Scientific Writing (topic position and stress position).
• 98 percent known words for unassisted reading: Hu and Nation (2000), and Nation (2006) on the vocabulary size that reaches it.
• Jargon costs fluency and engagement, and defining it does not fully repair the loss: Bullock et al. 2019 and Shulman et al. 2020.
• Long words lower judged ability: Oppenheimer 2006.
• Readability formulas are poor gates: Formulas, systems and LLMs are poor predictors of reading ease, plus the classic critiques of Flesch-Kincaid.