Why AI detectors flag your writing (and what to do about it)

You wrote every word yourself. You spent hours researching, drafting, and revising. Then, an AI detector flags your work at 85% AI-generated. What happened?

The answer isn't that you write like a robot, it's that AI detectors don't actually detect AI; they detect patterns that correlate with AI output. And some perfectly natural human writing triggers those patterns.

The five signals

Every major AI detector relies on some combination of five core signals. Understanding them is the first step to avoiding false positives.

1. Burstiness

Burstiness measures the variation in your sentence lengths. Humans naturally write with high burstiness: short punchy sentences mixed with longer more complex ones. AI tends to produce sentences of similar length, paragraph after paragraph.

If your writing has consistently medium-length sentences (15-25 words each), detectors notice. The fix isn't to write badly. It's to deliberately vary your rhythm. Follow a long compound sentence with something short. Break a pattern. Let your writing breathe.

2. Vocabulary density

AI models have a strong preference for certain words. We've covered the most common ones in detail in our post on the 6 phrases that trigger detection instantly. Certain phrases appear in AI output far more than they do in human writing. Detectors maintain lists of these "AI tells" and flag any text that uses them heavily.

The fix: search your writing for these common AI phrases. If you find yourself using them, ask whether a simpler, more natural alternative exists. "Also" works just as well as "furthermore" and won't trigger a flag.

3. Perplexity

Perplexity measures how predictable your word choices are. AI selects statistically likely next words, producing text with low perplexity. Human writing is messier: we use unexpected metaphors, colloquialisms, and personal references that an AI model wouldn't predict.

Low perplexity in your writing means a detector can predict your next word with high accuracy. That's a red flag. The fix: be yourself. Use your natural vocabulary, include personal examples, and don't over-edit casual phrasing into formal prose.

4. Structural patterns

AI loves structure. It produces consistent paragraph lengths, predictable topic sentences, and formulaic transitions. If every paragraph in your essay starts with a topic sentence followed by three supporting points and a conclusion, detectors will notice.

Real human writing has structural variety. Some paragraphs are long explorations; others are single-sentence punches. Some sections use lists; others use narrative. Vary your approach and your structure will read as authentically human.

5. Document coherence

This signal looks at the overall statistical fingerprint of your document. Detectors check the type-token ratio (vocabulary diversity), contraction rate, sentence length range, and other document-level metrics. A document that scores "too perfect" across all these metrics raises a flag.

The irony is that heavy revision can push these metrics into AI-like territory. When you polish every sentence to perfection, you inadvertently smooth out the natural variation that detectors look for.

The common thread

Notice the pattern? Every signal is essentially measuring the same thing: how polished and uniform your writing is. Detectors equate smoothness with AI and roughness with humanity. This is a flawed heuristic, but it's what we're working with.

The goal isn't to make your writing worse. It's to make it more authentically yours, which often means preserving the natural imperfections you'd normally edit out.

The targeted approach

You don't need to rewrite your entire paper. Most false positives come from a handful of sentences that score high on multiple signals at once. Fix those specific sentences and your overall score drops.

That's the approach GPTypo takes: scan your text, identify the specific sentences that trigger detection, see which signals they're hitting, and get rewrite suggestions that address those signals while preserving your meaning.

When you click a flagged sentence, GPTypo gives you rewrite suggestions you can accept as-is, edit to match your phrasing, or use as a starting point — the goal is a sentence that passes detection and still sounds like you.

The result is writing that's still yours, minus the handful of sentences that happened to look like AI output.