Can Turnitin Detect QuillBot? (2026 Update)
Yes — Turnitin can detect QuillBot paraphrasing in most cases. About 75% of AI-generated text run through QuillBot still gets flagged, and QuillBot-paraphrased passages average a 41% AI score on Turnitin's detector. Since December 2023, Turnitin has specifically trained its models to catch paraphrased AI text — and it marks it differently than raw AI output. Here's exactly what gets caught, which QuillBot modes perform worst, and what to do if you're already flagged.
Can Turnitin Detect QuillBot? (Yes — Here's Proof)
Turnitin detects QuillBot paraphrasing, and it's been getting better at it since late 2023. Their AIW-2 model (December 2023) added dedicated paraphrase detection, and the current AIR-1 model (July 2024) expanded that to catch rewritten text too.
The numbers tell the story. Only about 1 in 4 AI passages paraphrased through QuillBot drops below Turnitin's 20% detection threshold. The other three out of four still get flagged. QuillBot-paraphrased text averages a 41% AI score on Turnitin — well above the threshold where professors start asking questions.
These aren't just statistics. In one widely discussed 2024 case, a student's climate change essay was flagged at 92% AI confidence after being run through QuillBot's paraphraser. The student had used ChatGPT for a rough draft, paraphrased it through QuillBot, and assumed the output would pass. It didn't come close.
QuillBot gets caught by other detectors too. Here's how the major detectors compare on QuillBot-paraphrased AI text:
| Detector | Approximate Detection Rate on QuillBot |
|---|---|
| GPTZero | ~91% |
| Originality.ai | ~94.66% |
| Turnitin | ~70% |
Turnitin's ~70% detection rate for QuillBot is actually the lowest among major detectors. That might sound like good news, but it isn't — Turnitin is the one your university uses. GPTZero and Originality.ai catch more, but they're not integrated into most LMS platforms. If your professor runs your paper through one of those tools manually (and an increasing number do), the detection rate jumps significantly.
QuillBot's own help center acknowledges that Turnitin may flag QuillBot-paraphrased content. They don't promise their tool beats detection — because it doesn't.
Understanding how AI detectors work — the perplexity and burstiness scoring behind every major tool — explains why QuillBot's synonym swaps don't fool the algorithms.
How Turnitin Catches QuillBot Paraphrasing
QuillBot changes words and sentence structures, but it doesn't change the underlying statistical patterns that Turnitin looks for. This is the key distinction most people miss.
Turnitin's AI detector doesn't check whether specific words match a database. It analyzes how predictable the word sequences are. AI-generated text — even after paraphrasing — follows probability distributions that human writing doesn't. QuillBot swaps vocabulary and rearranges clauses, but the "flow" of the text still reads like a machine wrote it.
Think of it this way: if someone translates a book from English to French, the French version is entirely different words. But the story structure, pacing, and logic are identical. QuillBot does something similar — it changes the surface while leaving the deep structure intact. Turnitin reads that deep structure.
Turnitin's instructor dashboard even distinguishes between the two types of AI use. Text flagged as AI-generated from scratch appears in cyan highlighting. Text identified as AI-generated and then paraphrased shows up in purple. Your professor can see not just that AI was involved, but that a paraphrasing step was used — which actually looks worse than raw AI text, because it suggests an attempt to hide the source.
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Turnitin uses two-tier highlighting on its instructor dashboard: cyan marks text identified as AI-generated, and purple marks text identified as AI-generated then paraphrased. Professors can see that a paraphrasing tool was used, which may suggest intent to disguise AI use.
QuillBot Mode-by-Mode: Which Gets Caught Most?
QuillBot offers several paraphrasing modes, and they don't all perform the same against Turnitin. No independent study has published rigorous mode-by-mode Turnitin scores, but community testing and smaller-scale analyses give a consistent picture:
| QuillBot Mode | Typical Turnitin AI Score | Detection Likelihood |
|---|---|---|
| Standard | 55–65% | High — almost always flagged |
| Fluency | 50–60% | High — minimal rewording |
| Formal | 45–55% | High — still predictable patterns |
| Creative | 30–45% | Moderate — most variation, but inconsistent |
| Shorten | 60–70% | Very high — compresses without changing patterns |
| Humanize (Beta) | 35–50% | Moderate — designed to beat detectors, often doesn't |
Creative mode produces the most variation because it takes the most liberties with your text. It changes sentence structures more aggressively and introduces less predictable vocabulary. That's why it scores lowest — but "lowest" still means 30–45%, which is above Turnitin's 20% flag threshold in most cases.
Shorten mode is the worst choice. It compresses text without fundamentally altering its patterns, giving Turnitin's detector an easy target.
Humanize mode is QuillBot's newer addition, explicitly designed to make text sound more human. It's a tacit acknowledgment that their other modes get caught. In testing, it performs slightly better than Formal but worse than Creative on Turnitin — and it's inconsistent. Some passages score in the 30s; others land in the 50s from the same input. It also tends to degrade meaning more than other modes, producing awkward phrasing that a professor would notice even if the detector didn't.
Free QuillBot limits you to Standard and Fluency — the two modes with the highest detection rates. Premium unlocks Creative, but even Creative doesn't reliably beat detection. The difference between free and paid is marginal when it comes to Turnitin.
Worth noting: university policies on paraphrasing tools vary wildly. Some schools treat QuillBot the same as ChatGPT — any use is a violation. Others allow it for grammar assistance but not for rewriting paragraphs. A handful haven't updated their policies to address paraphrasing tools at all. Check your school's academic integrity policy before assuming QuillBot is safe to use, regardless of which mode you pick.
What about stacking QuillBot with manual editing afterward? For a side-by-side comparison of how paraphrasers and dedicated humanizers perform against Turnitin, see our AI humanizer vs paraphraser breakdown. This combined approach — paraphrasing first, then rewriting by hand — does lower detection rates more than QuillBot alone. But "lower" doesn't mean "safe." Turnitin's AIR-1 model was specifically trained to catch rewritten AI text, and heavily edited QuillBot output still lands in the 25–40% range in most tests. The manual effort required to push below 20% is close to the effort of just writing the paper yourself.
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QuillBot's Creative mode produces the lowest Turnitin AI scores (30–45%), but even this rarely drops below the 20% threshold where Turnitin stops flagging. Standard and Fluency modes — the only ones available for free — score 50–65% and get caught almost every time.
What If You Used QuillBot on Your Own Writing?
This is the scenario that doesn't get enough attention. Thousands of students use QuillBot not to disguise AI text, but to polish their own human-written work — especially non-native English speakers who rely on it for grammar and fluency.
The problem: QuillBot's corrections can make your writing more detectable, not less. When it smooths out your grammar, standardizes your sentence lengths, and replaces informal vocabulary with formal alternatives, the result reads more like machine-generated text. The natural irregularities that prove you're human — odd word choices, varied rhythm, the occasional clumsy sentence — get sanded away.
This is one reason why your own writing might get flagged even without any AI involvement. Non-native speakers are hit hardest here, and the mechanics are worth understanding. If English is your second language, you probably already write with simpler sentence structures and more common vocabulary — the same patterns AI detectors associate with machine-generated text. When you run that text through QuillBot to improve your grammar, it makes the patterns even more uniform. It standardizes your punctuation, regularizes your sentence lengths, and replaces your informal word choices with formal alternatives. The result reads like it was generated by a machine — not because it was, but because both QuillBot and ChatGPT optimize for the same kind of "correct" English.
Stanford's Liang et al. found that 61.3% of TOEFL essays by non-native speakers were falsely flagged as AI-generated across seven detectors. Those essays were written without any AI assistance at all. Add QuillBot into the mix and the problem compounds.
Turnitin acknowledges this limitation. Scores in the 1–19% range display an asterisk (*), and Turnitin explicitly tells instructors not to treat those scores as evidence. But not every professor reads the fine print.
If you used QuillBot only to fix grammar on text you wrote yourself, you have a strong case. The key is proving it — which means having your original draft before QuillBot touched it.
What to Do If Turnitin Flags Your QuillBot-Paraphrased Paper
Your next steps depend on whether you used QuillBot on AI-generated text or on your own writing. Either way, don't panic — a Turnitin flag is the start of a process, not a verdict.
If you paraphrased your own human-written text:
- Gather your original draft — the version before QuillBot. Google Docs version history, saved Word files, even screenshots work.
- Show your professor the before-and-after. When they can see your original writing alongside the QuillBot-polished version, it's clear you wrote the content yourself.
- Explain why you used QuillBot. If English isn't your first language, say so. If you used it for grammar help, that's a legitimate use case that QuillBot themselves support.
- Check your university's policy on paraphrasing tools. Some schools explicitly allow QuillBot for grammar assistance. Others ban all AI-assisted writing tools. Know the rules before your meeting.
If you paraphrased AI-generated text:
The honest truth: your options are limited. Turnitin's purple highlighting specifically indicates AI text that was paraphrased, and that's hard to explain away. Denying it when the evidence is color-coded on your professor's screen will make things worse, not better.
Your best path forward is to understand your university's academic integrity process and prepare your case for any hearing. Key factors that affect your outcome: Is this your first offense? (First offenses usually get lighter penalties.) Does your school distinguish between full AI generation and AI-assisted writing? (Some do, with lighter penalties for the latter.) Did you use AI for the entire paper or just sections? (Partial use is typically treated more leniently than wholesale submission.)
If your school offers an academic integrity hearing, bring context — not excuses. Explaining that you used ChatGPT for a rough framework but rewrote sections yourself, if true, demonstrates a different level of engagement than copying and pasting a full essay. Some institutions accept a redo assignment as resolution for first-time offenders.
For either situation:
Keep every draft from now on. Write in Google Docs so your version history is automatic and timestamped. If you use any editing tools — Grammarly, QuillBot, or anything else — save your text before and after. As of March 2026, Turnitin's broader AI detection capabilities keep improving with each model update, and the paraphrasing loopholes are closing fast.
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QuillBot's own help center states that "using QuillBot is not cheating" when used as a writing assistant on your own work. If you're flagged for using QuillBot on human-written text, this official position — combined with your original draft — is your strongest defense.