Google Docs add-on

How to Check a Google Doc for AI Writing

Updated

Short answer

To check a Google Doc for AI writing, add the Plagiarism Checker Plus add-on to Google Docs™, open your document and choose Extensions › Plagiarism Checker Plus › Check this document. Tick AI-generated text, click Check document, and the sidebar shows an overall AI score plus the passages that look AI-written. You can highlight those passages right in the doc.

Before you start

  • A free account. The add-on doesn’t offer guest checks, so you’ll sign in the first time you use it. You can create an account for free on the sign-in page.
  • At least 50 words. Shorter text doesn’t give the detector enough to work with, so checks under 50 words aren’t accepted.
  • The add-on installed. See How to install and use the Google Docs add-on.
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Check a Google Doc for AI writing

  1. Open the document in Google Docs in your web browser.
  2. In the menu bar, choose Extensions › Plagiarism Checker Plus › Check this document. The sidebar opens on the right.
  3. If you haven’t signed in yet, click Sign in and finish signing in in the window that opens. The sidebar picks up your account automatically.
  4. Choose Whole document, or select a passage first and choose Selection to check only that part.
  5. Under Look for, tick AI-generated text. Tick Plagiarism as well if you want both checks in one go.
  6. Click Check document (or Check selection). Long documents can take a few minutes — you can keep writing while the check runs.
  7. Open the AI content tab to see the score and the flagged passages.

Reading the AI results

The AI content tab shows an overall score with a short verdict, followed by the passages the detector thinks are most likely AI-written. Each passage is tagged Highly likely, Likely or Possible. Sentences the detector rates below 40% aren’t listed at all, so a short list usually means most of the document reads as human-written.

Click a passage (or Show in document) and the add-on selects that text in your document so you can see it in context. To mark every flagged sentence at once, tick Highlight AI sentences in document — they get a pale yellow background. Clear removes the add-on’s highlights and puts back any colour that was there before. More in Highlighting matches in your doc.

Want the full picture? Open full report opens the same check on the Plagiarism Checker Plus website, with the complete sentence-by-sentence breakdown. For what the numbers mean, see How to read your plagiarism and AI scores.

If you edit the document afterwards

After a whole-document check, the add-on notices when the text changes. The status line then says Document edited since last check and offers Re-check, so you don’t mistake old results for new ones. Closing and reopening the sidebar brings back the last check for that document.

Keep the score in perspective

No AI detector is perfect. Formal or formulaic writing, text by non-native English speakers, and heavily edited drafts can be misread, and AI-written text can slip through. Treat the result as a signal to look closer, not as proof — especially before making a decision about someone else’s work.

If you’re reviewing a student’s or colleague’s document, the score works best alongside other context, such as earlier drafts and the document’s version history. See Can Google Docs detect AI writing? for what Docs itself can show you.

Checking without the add-on

You can also copy the text into our AI detector on the website. The Chrome™ extension’s in-page buttons don’t run inside Google Docs, so for Docs the add-on is the way to check in place.

Still need help?

Tell us what you were trying to do and what happened. Email contact@plagiarismcheckerplus.com or use the contact form.

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