Turnitin AI detection explained
Turnitin AI detection runs inside schools and universities, and students cannot buy it themselves. This page explains how it works according to Turnitin's own documents, who sees the score, and where Textlume fits if you want to read your own draft first.
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The short answer
Turnitin gives instructors an AI writing percentage next to the similarity report. By its own 2023 update it needs at least 300 words of prose and shows scores under 20% as an asterisk. Students reach it only through their institution. Textlume is a separate detector you can use on your own text. Its score will not match Turnitin's, and we have not measured how the two compare.
Where the two really differ
- Who runs the check. Turnitin is licensed by institutions and the instructor reads the report. On Textlume you run the check on your own text and see the full result.
- Length. Turnitin's 2023 update asks for at least 300 words of prose. Textlume also reads shorter texts and marks the confidence as low when a text is short.
- What the score covers. Turnitin reports an overall percentage with highlighted segments. Textlume scores the whole text and every sentence, with a range around the overall score.
- Rewritten text. In English, Turnitin flags text changed by AI bypasser and paraphrasing tools. Textlume gives no advice on hiding AI use and never predicts what Turnitin will show.
Turnitin and Textlume side by side
| Feature | Turnitin | Textlume |
|---|---|---|
| Free tier | None for individuals. Access comes through a school or university licence. | 1 free run a day per tool, up to 250 words in the detector and 150 in the humanizer. No account, no card. |
| Price | No public price. Sold to institutions. | From 6.99 USD a month billed yearly, or 9.99 USD month to month. |
| Words and limits | At least 300 words of prose for an AI score, per its 2023 update. | Detector: 50,000 to 300,000 words a month, up to 10,000 per check. Humanizer: 10,000 to 50,000 words a month. |
| Languages | English, Spanish, Japanese and Arabic. Since October 2026 also German, Dutch and Turkish. | 13 calibrated text languages for AI detection. Other languages get no score. |
| Published accuracy figures | Under 1% document false positives above 20% AI writing, about 4% at sentence level, by its own 2023 figures. | Held-out counts per language, with sample sizes, on our accuracy page. |
| Sentence marks | An overall percentage with highlighted segments. Scores under 20% show as an asterisk. | Yes. Every sentence gets a score, next to an overall score with a range and a confidence rating. |
| Humanizer | None. It flags text changed by bypasser tools, in English. | Yes. Academic, professional and casual tabs, and names, numbers and quotes stay as they are. |
| API | Only through institutional licences. | On the Pro plan, for detection, humanizing, paraphrasing, summaries and grammar. |
| Plagiarism check | Similarity Report against Turnitin's own database. | Coming soon. Not open for checks yet. |
What Turnitin and Textlume cost
Turnitin
- Turnitin OriginalityNo public price
Price on request from sales
Similarity checking for institutions, with AI writing detection where the institution licenses and enables it.
Textlume
- Basic6.99 USD
Per month, billed yearly. Monthly: 9.99 USD.
50,000 detector words, 10,000 humanizer words and 10,000 paraphraser words a month, plus 20 runs of clarity suggestions a day.
- Plus9.99 USD
Per month, billed yearly. Monthly: 19.99 USD.
150,000 detector words, 25,000 humanizer words and 25,000 paraphraser words a month, plus 30 runs of clarity suggestions a day.
- Pro12.99 USD
Per month, billed yearly. Monthly: 29.99 USD.
300,000 detector words, 50,000 humanizer words and 50,000 paraphraser words a month, plus 40 runs of clarity suggestions a day. API access included.
Where Turnitin is ahead
- Its similarity check compares work with Turnitin's own database, which a search of the open web cannot reach.
- The AI score sits inside the instructor's existing Similarity Report workflow.
- In English it also highlights text changed by AI bypasser tools and AI paraphrasing.
- It reads Japanese with a dedicated model, and since October 2026 also German, Dutch and Turkish.
How Textlume works
- Anyone can use it, with a free daily check of 250 words, no account and no card.
- You see the full result yourself: an overall score with a range, a confidence rating and a mark on every sentence.
- Low scores are shown as numbers too, never hidden.
- Our accuracy page lists held-out false-flag counts per language, including writing by non-native speakers.
- After the reading you can work on the draft in the same editor, with a grammar checker, a paraphraser or a summarizer.
Which one suits your work
Pick Turnitin if
you teach or run integrity checks at an institution and need similarity reports against Turnitin's database with AI scores inside the grading workflow. Students do not choose Turnitin, their institution does.
Pick Textlume if
you want to read your own draft before you hand it in, see which sentences look machine-written and how sure the reading is, and tidy the text with a grammar checker or paraphraser, knowing that no outside tool can tell you what Turnitin will show.
Questions people ask before choosing
ContactHow does Turnitin AI detection work?
Turnitin reads a submitted document and gives the instructor an overall percentage of text that is likely AI-generated, with the segments it suspects highlighted. Its 2023 update set a minimum of 300 words of prose and shows scores under 20% as an asterisk. It reads English, Spanish, Japanese and Arabic, and since October 2026 also German, Dutch and Turkish.
Can students see their Turnitin AI score?
That depends on the institution. Turnitin writes its AI guidance for instructors, and the AI score sits in the instructor's Similarity Report workflow. Ask your instructor or your school's guidance page whether students are shown it.
Does Turnitin detect ChatGPT?
Turnitin's detector is built to flag text that is likely written by large language models such as those behind ChatGPT. Its Japanese model, for example, was trained on output from GPT-4, GPT-4o and GPT-4o-mini. Turnitin also tells instructors to apply their own professional judgment to every score.
What does the asterisk in a Turnitin AI score mean?
Turnitin shows an asterisk instead of a number when it detects less than 20% AI writing in a document, because it treats those low scores as less reliable. That rule comes from its May 2023 product update.
What is Turnitin's false positive rate?
By Turnitin's own 2023 figures, under 1% at document level for documents with over 20% AI writing, and about 4% at sentence level. Those are its numbers. We have not tested Turnitin.
Can I check my paper with Turnitin before I submit it?
Not as an individual student. Turnitin's help center says it does not sell individual licences and names iThenticate as the option for individual users. Textlume lets you read your draft with a free daily check, but its score will not match what Turnitin shows.
Does Turnitin detect humanized text?
Turnitin added detection of text changed by AI bypasser tools, and it highlights AI-paraphrased text too. Its own announcement says this works on English submissions only. The Textlume humanizer makes no promise about passing any detector.
Which languages does Turnitin AI detection cover?
English, Spanish, Japanese and Arabic, with separate models for Spanish and Japanese. Its release of 6 October 2026 adds German, Dutch and Turkish, through Turnitin Originality and as an add-on for iThenticate 2.0. The bypasser detection covers English only. The Textlume detector is calibrated for 13 text languages.
What should I do if Turnitin flags my work?
Ask to see the report and which passages were highlighted. Bring your notes, drafts and the document's version history to the conversation. Turnitin tells instructors that a score calls for their professional judgment, so the score opens a discussion and should not end it.
Does Textlume have a similarity check like Turnitin?
Our plagiarism check is coming soon and not live yet. Once it opens, it will search the open web on paid plans. It cannot see student-paper databases or paywalled journals, so it is no replacement for Turnitin's similarity report.
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