Why em dashes give away AI writing

Updated 2026-09-20 · a working page, not a sales page

Nobody has ever been fired for an em dash. But readers who spend their day looking at generated text start noticing clusters of them, because people typing quickly rarely reach for the character.

Short answer

What the mark is doing

Models use the em dash as a rhythm shortcut: it lets them add an aside without committing to a new sentence. Human writing does that too, but a person under time pressure usually starts a new sentence or drops the aside entirely.

So the practical tell is not the character. It is the pattern of small qualifications appended to main clauses — always present, never developed.

When to keep it

Keep it when the aside genuinely interrupts: 'The file — all 112,318 bytes of it — arrived twice.' Keep it for a hard turn in dialogue or a range where a dash is clearer than punctuation. Delete it when the aside restates the main clause in different words, which is most of the time.

A 30-second pass

Find every dash in the draft. For each one, ask whether the clause before or after is doing new work. If one of them is a repeat, you have four options in order of preference: delete the repeated clause, split into two sentences, use a colon if the second half explains the first, and only then leave the dash.

Before / after

What people usually writeWhat it looks like after
The tool is fast — it processes your draft in seconds — and accurate — because it keeps your facts intact.It keeps your facts and returns a draft in a few seconds. That is the whole product.
Shipping is slow — around two weeks — but reliable — we have not lost a parcel this year.Shipping takes about two weeks. We have not lost a parcel this year.
It is not a rewriter — it is a thinking partner — and that distinction matters.It does not rewrite. It asks what you are actually trying to say.
What this page will not do. Avoiding dashes will not make text sound human on its own, and using them does not prove a machine wrote something. This is one weak signal among several, not a detector.

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Questions

Is the em dash an official AI signal?

No. It is a community heuristic with no reliable statistics behind it. Treat it as a reason to re-read, not a verdict.

What about en dashes and hyphens?

Different characters with different jobs: ranges, compound words, minus signs. Readers rarely react to those.

Should I remove all em dashes from my writing?

No. Remove the ones that are covering for a sentence you should have deleted.