Copyleaks vs Turnitin

• You are not an instructor at a Turnitin school
• You want plagiarism and AI checks in one report
• You work across languages
• You check short pieces or images

• Your institution already licenses Turnitin Originality
• You want the cautious default
• You grade long-form English that may have been paraphrased

Turnitin does not sell individual licenses or single-use subscriptions, according to its help center article updated 3 June 2026 and checked 23 October 2026.

Sources: Copyleaks' pricing page, Copyleaks' AI detector page, Copyleaks' testing methodology, Turnitin's AI writing detection FAQ (updated 14 October 2026) and Turnitin's individual license article, all opened 23 October 2026.

I'd pick Copyleaks unless your school already licenses Turnitin, because Turnitin sells only to institutions. Copyleaks Personal costs USD 16.99 a month and checks AI and plagiarism in one report, in 30+ languages. Turnitin shows its AI report to instructors only and hides scores from 1% to 19%. Neither score is proof on its own.

Choose Copyleaks if

• You are not an instructor at a Turnitin school. Copyleaks sells Personal and Pro plans to anyone, and its AI detector page lets you scan up to 25,000 characters without logging in.
• You want plagiarism and AI checks in one report. Copyleaks' AI Logic report puts matched sources and the AI prediction side by side for text.
• You work across languages. Copyleaks lists AI detection in 30+ languages, and Pro adds detection of plagiarism translated from another language.
• You check short pieces or images. The methodology page sets a 350-character minimum, and Personal includes AI image detection.

Choose Turnitin if

• Your institution already licenses Turnitin Originality. The AI writing indicator appears in the Similarity Report inside your LMS, with nothing new to buy.
• You want the cautious default. Turnitin shows no number for AI scores from 1% to 19%, which keeps low, unreliable results out of a grade conversation.
• You grade long-form English that may have been paraphrased. Turnitin's FAQ says English submissions are checked for text modified by AI paraphrasers and bypassers.

Both score text with a trained model and highlight the passages behind the score. Both run inside the main learning management systems, both offer plagiarism matching next to AI detection, and both say a result should start a review, not end one. Turnitin's FAQ says the percentage "should not be used as the sole basis for action".

Both also warn about writing assistants. Turnitin says ordinary grammar fixes are mostly not flagged, but text from generative features such as drafting and paraphrasing likely will be. Copyleaks' AI detector page says tools that use generative models for key functions can be flagged as potential AI content.

Copyleaks

• Best for: individuals, editors, small teams and schools that want AI and plagiarism checks in one report across many languages.
• Main limitation: Copyleaks' privacy policy says it uses customer content to train its models; direct customers opt out by contacting support, and enterprise customers decide for their users. Scans compared against the Shared Data Hub are stored there unless you disable it.
• Price or plan limits (checked 23 October 2026): Personal USD 16.99 a month with 100 credits, or USD 13.99 a month billed annually with 1,200 credits; Pro USD 99.99 a month with 1,000 credits, or USD 74.99 a month billed annually with 12,000. One credit covers up to 250 words or one image.

Turnitin

• Best for: instructors and integrity officers at schools that license Turnitin Originality.
• Main limitation: students cannot see the AI report unless an instructor shares a PDF, and nobody can buy it alone. Turnitin's FAQ says it accepts missing some AI text to hold its false positive target, so a 50% score "could contain as much as 65% AI writing".
• Price or plan limits (checked 23 October 2026): no list price; sold only to schools, universities and organizations. AI writing needs Turnitin Originality, or the AI writing add-on for iThenticate 2.0.

On unedited AI text, the one peer-reviewed study that ran both on the same papers found them equal. William Walters tested 16 detectors on 126 undergraduate papers: 42 written by students in 2014 and 2015, and 84 generated by ChatGPT-3.5 and GPT-4. Copyleaks and Turnitin each classified all 126 papers correctly, with no wrong or uncertain answers (Open Information Science, 2023). Originality.ai came third at 98%.

Three limits keep that result from settling the question:

• The versions are old. Walters ran his tests from 25 June to 12 July 2023. Both vendors have changed their models since; Copyleaks' methodology page now describes model V11.
• The texts were unedited. Walters names paraphrased and edited AI text as the study's most significant gap. Turnitin's FAQ says it checks English submissions for AI paraphrasing and bypasser tools; Copyleaks offers an Extra Sensitive setting aimed at spun text.
• Turnitin may have seen the human papers. Walters notes the student papers could have been used to train Turnitin's detector, which may flatter its score on that set.

Earlier studies that Walters summarized show more spread for Copyleaks. On unmodified ChatGPT text, one 2023 study found Copyleaks caught 97% of AI samples and another 23%, while Turnitin scored 91% to 97% across the studies that included it. On human text, Copyleaks scored 92% to 93% correct and Turnitin 100% in the studies listed. Different sample types, model versions and scoring rules explain much of that gap.

Every published head-to-head predates the 2026 versions. Until a new one appears, I compare the vendors' own figures side by side: Copyleaks reports a 0.30% false positive rate at its default setting on its methodology page, and Turnitin targets under 1% for documents with over 20% AI writing.

In practice, the two will often disagree on the same essay because they report differently. Turnitin hides any AI score from 1% to 19% and needs at least 300 words of prose; Copyleaks shows every score and works from 350 characters. A low Copyleaks score next to a Turnitin asterisk is not a contradiction. For the wider evidence on errors across tools, see GPTZero vs Copyleaks and my Copyleaks review.

Both vendors publish their own error rates, and both figures come from their own tests.

• Copyleaks' figure. Copyleaks reports a 0.30% false positive rate at its default Balanced setting, from tests on English text by its own teams, published 28 September 2026. Its QA set flagged 6 of 74,212 student essays as AI. The AI detector page states a different figure, 0.03% (both checked 25 October 2026).
• Turnitin's figure. Turnitin aims to keep the document false positive rate under 1% for documents with over 20% AI writing, validated on more than 700,000 academic papers written before ChatGPT.
• The category. Weber-Wulff and colleagues tested 14 tools, including Turnitin, and concluded that the available detection tools are "neither accurate nor reliable" (International Journal for Educational Integrity, 2023). Turnitin scored highest of the 14, and no tool reached 80% accuracy under the authors' binary method.
• Non-native writers. Liang and colleagues found seven detectors misclassified over half of TOEFL essays as AI-generated, with an average false positive rate of 61.22% (Patterns, 2023). The mechanism they describe, plainer vocabulary reading as machine-like, applies to any detector.

Copyleaks reported a 0.30% false positive rate for its default AI detection setting in September 2026, from vendor-run tests on English text on its testing methodology page; its AI detector page states 0.03%.

Guidance from Jisc, the UK education technology body, says no AI detection software can conclusively prove text was written by AI. Vanderbilt University disabled Turnitin's AI detector in August 2023, and my Turnitin AI detection review covers later university decisions and the student appeal process.

Because the tools report differently, the same essay can come back with results that look contradictory. Here is how I read the common combinations.

My take: agreement between two detectors raises my attention, not my certainty. Both models learned from similar kinds of text, so they can share the same blind spots, especially on plain or non-native writing.

1. Build a labeled set: 10 texts you know are human, including non-native English writing, 10 generated texts and 10 generated texts edited by a person. Keep every text above 300 words so Turnitin can process it.
2. Run each text through both tools on the same day, through your school's Turnitin assignment and a Copyleaks account at its default setting.
3. Record Turnitin's asterisks separately. A hidden 1% to 19% result is not the same as 0%.
4. Count false positives apart from missed AI text. One wrongly flagged essay costs more than one missed generated paragraph.
5. Test plagiarism separately with a copied passage, since text matching and predicted AI authorship answer different questions.
6. Decide what a flag triggers: a conversation and a look at drafts, never a penalty on its own.

Read my guide to AI detector false positives, the AI detectors shortlist, and my guide to the Turnitin similarity score for the plagiarism side of the report.