The only honest answer is an estimate. A detector can show which sentences read like AI-written text, but none can prove who wrote them. Run the free PaperCheck check to see exactly which sentences are flagged, then judge them yourself.
Written by Adithyan, a student who builds PaperCheck. Last updated 2 November 2026.
AI detectors score how predictable and uniform a passage is: repeated sentence shapes, stock transitions ("Moreover", "it is important to note"), and even sentence length. Human writing is usually less even. Careful human writing can still be flagged, especially by non-native English writers.
Each detector is trained differently and uses its own threshold. A paper can show 10% on one and 60% on another. That is why a result is an estimate. See why Turnitin, GPTZero and Pangram give different scores.
Keep your drafts, notes and version history. They are the best evidence. Rewriting the flagged sentences with specific details from your work usually lowers the score too. See do AI detectors flag non-native English writing?
No. It gives an estimate based on writing patterns, not proof of authorship.
Yes. False positives happen, more often for non-native English writers.
Yes: 5 free checks a week, up to 20,000 words each.
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PaperCheck is not affiliated with Turnitin, GPTZero, papercheck.in or papercheck.ai. Scores from any detector are estimates, not proof.