AI text detector

Gemini text detector

Gemini writes inside Gmail, Docs and Search as well as in its own app, so its text turns up in emails, reports and web pages. Paste a passage to see which AI-writing signs it shows.

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Gemini’s house style

Gemini answers are built to be skimmed. A typical response opens with a one-sentence summary, often in bold, then breaks the topic into headed sections with bulleted points, each starting with a bold label and a colon. Comparisons go into tables. It closes with a short wrap-up and, in the app, an offer to go deeper. When that structure is pasted into an email, a forum post or an essay, the scaffolding comes along: stray asterisks, pound-sign headings, and title-case section names on their own lines.

GPTTrace looks for exactly these artifacts. It highlights Markdown that didn’t render, title-case headings, “**Label:**” bullet patterns and the emoji bullets that Gemini and other assistants use in casual answers. These are formatting habits, not proof — some people write in Markdown — but in ordinary prose they are a strong indicator of copied chat output.

Beyond formatting

Strip the formatting and Gemini’s prose shares the general signs of AI writing: explanations that move in neat three-part steps, vague attributions like “experts note”, emphatic claims of significance and smooth transitions such as “Additionally” and “Furthermore”. Its encyclopedic tone is a particular challenge, because human-written reference text uses the same register — which is why GPTTrace weights the signs using measured data instead of treating each as damning.

Because Gemini is embedded in Google Workspace, a lot of its text arrives as lightly edited business writing: meeting summaries, project updates, customer emails. These are often short. Below about 150 words any detector, including this one, should be treated as a rough indication only.

Gemini images and audio

If the question is about a picture rather than a paragraph, Google labels its generated images with metadata that GPTTrace can read — see the Gemini image detector. For songs or voices from Google’s audio models, use the AI audio detector.

Checking AI text in work email

Many organisations now allow Gemini or similar assistants for drafting, so AI involvement in an email is not in itself a problem. Detection matters when authorship matters: a personal statement, a reference letter, a complaint presented as a customer’s own words, or a phishing email impersonating a colleague. For phishing in particular, the content of the request — urgency, payment, credentials — is a better warning sign than the writing style, and modern scams are often fluent precisely because they are written by AI.

For long internal documents, check a few sections separately. Mixed authorship is normal in collaborative work: one section may be drafted by Gemini and others written by hand, and checking the whole document at once averages them out.

How accurate is it? Our measured numbers

We test GPTTrace on labelled text samples and publish the results, including where it does badly. It is tuned to keep false accusations rare, so it misses some AI content rather than flag real work.

standard text check: AUC 0.795 (cross-validated)

2,467 labelled samples (1,258 AI, 1,209 human), run 2026-10-08. At the “Likely AI” line it caught 34% of AI samples and wrongly flagged 5% of human ones.

SourceTruthSamplesResult at “Likely AI”
claude-opus-5AI1250% caught
gpt-4.1AI12100% caught
gpt-oss-120bAI12100% caught
claude-haiku-4-5AI1283% caught
qwen-3.8-27bAI863% caught
pd-literatureHuman3061% wrongly flagged
human-pmc-eslHuman1835% wrongly flagged
human-wikipedia-pre2022Human1558% wrongly flagged
hc3-open_qaHuman714% wrongly flagged
chatgpt-3.5AI120232% caught
hc3-wiki_csaiHuman5586% wrongly flagged

text check with deep scan: AUC 0.91 (cross-validated)

2,467 labelled samples (1,258 AI, 1,209 human), run 2026-10-08. At the “Likely AI” line it caught 56% of AI samples and wrongly flagged 5% of human ones.

SourceTruthSamplesResult at “Likely AI”
claude-opus-5AI1242% caught
gpt-4.1AI12100% caught
gpt-oss-120bAI12100% caught
claude-haiku-4-5AI12100% caught
qwen-3.8-27bAI875% caught
pd-literatureHuman3060% wrongly flagged
human-pmc-eslHuman1831% wrongly flagged
human-wikipedia-pre2022Human1551% wrongly flagged
hc3-open_qaHuman70% wrongly flagged
chatgpt-3.5AI120254% caught
hc3-wiki_csaiHuman5589% wrongly flagged

Data sources and method: methodology & accuracy.

Frequently asked questions

Does Google watermark Gemini’s text with SynthID?
Google has said it applies SynthID text watermarking to some Gemini output. The watermark can only be checked with Google’s key, so GPTTrace can’t read it; it analyses the writing itself instead. See our SynthID guide.
What does Gemini’s writing look like?
Heavily structured: a bolded summary line, headers, bullet lists with bold lead-ins, tables for comparisons, and a closing offer to help further. In prose it tends toward clear, encyclopedic explanations with phrases like “Here’s a breakdown” and “Key takeaways”.
Will text from “Help me write” in Gmail be detected?
Short emails are hard for any detector because there are too few words. Longer drafted emails and documents often show the same signs as other chatbot text, especially if they were sent without editing.
Is the formatting itself evidence?
When Markdown symbols appear where they don’t render — asterisks around words in a plain-text email or a web form — it is a strong sign the text was pasted from a chat interface, and GPTTrace flags it.