// AI detectors
Turnitin AI writing detection
Built into Turnitin’s similarity reports – sold to schools, not to individuals.
official sources onlychecked 2026-10-26
⚠ AI detection can misjudge. Turnitin: the AI score “should not be used as the sole basis for adverse actions against a student”.
01At a glance
| Official link | https://www.turnitin.com/ |
|---|---|
| Made by | Turnitin LLC |
| Free? | Not free and not sold to individuals – access is through your institution’s licence. |
| Paid | Institutional licences (pricing on request). |
| Languages | English; Spanish (since Sept 2024); Japanese (since April 2025). |
| Files | Submissions through the institution’s Turnitin workflow (file types per Turnitin’s submission rules). |
| Limits | Up to 30,000 words; below 300 words results are less reliable. Scores of 1–19% are shown as “*%”. |
| Best for | Universities and schools. |
02How to use it
- Submit through your institution’s Turnitin assignment.
- Instructors see the AI writing indicator in the report.
- Treat “*%” and short submissions with extra caution.
03Accuracy
Turnitin publishes no single accuracy number on the guide we checked. In Weber-Wulff et al. (2023) Turnitin had 0% false positives in that test set, but all tools scored below 80% accuracy overall.
Independent evaluations:
- Weber-Wulff et al. (2023), “Testing of detection tools for AI-generated text”, International Journal for Educational Integrity — 14 tools tested (12 public + Turnitin and PlagiarismCheck): all scored below 80% accuracy and only 5 above 70%; the authors conclude the tools are “neither accurate nor reliable”. False positives ranged from 0% (Turnitin) to 50% (GPTZero) on their test set; machine paraphrasing cut accuracy to 26%. English texts, tested in 2023 – tools have changed since.
- Liang et al. (2023), “GPT detectors are biased against non-native English writers”, Patterns — Several widely used GPT detectors “consistently misclassify non-native English writing samples as AI-generated, whereas native writing samples are accurately identified”; simple prompting can also bypass them. The authors caution against using detectors in evaluative or educational settings.
04FAQ
FAQ
Can individuals buy Turnitin AI detection?
No – Turnitin licenses institutions. Sites selling “Turnitin checks” to individuals are not Turnitin.
Why does Turnitin show *% ?
Scores between 1% and 19% are shown as *% because they are less reliable.
Can Turnitin AI writing detection be wrong?
Yes – AI detection can misjudge. Turnitin: the AI score “should not be used as the sole basis for adverse actions against a student”.
05Official sources
Checked against these pages on 2026-10-26; the official page wins if anything differs.