QuillBot's AI Detector gives pasted text a 0 to 100% score and labels it AI-written, AI-refined or human-written. QuillBot says never to make an academic decision on that score alone.
The QuillBot AI detector estimates the likelihood that pasted text was generated by artificial intelligence (AI), but its score serves as a preliminary signal rather than definitive proof. The QuillBot detector accepts pasted text and generates an overall score from 0 to 100 percent representing the probability of automated writing.
QuillBot breaks its analysis into three distinct classifications:
The interface provides section-by-section feedback and presents explainer cards detailing why specific sentences triggered an alert. However, QuillBot explicitly states that no AI detector can provide 100 percent accuracy. QuillBot's detector page says scores are signals and should not be read as verdicts. QuillBot tells educators and employers never to make an academic disciplinary or employment decision based solely on a detector score.
QuillBot claims a 99 percent detection rate on the third-party RAID benchmark dataset. QuillBot's own page also lists cases where its scores are less dependable. When the model encounters ambiguous phrasing, it tends to classify the text as human-written. Conversely, formulaic human writing, such as academic definitions or structured templates, can register unexpectedly elevated AI probability scores. Because of these structural limitations, educators wondering are AI detectors accurate must treat any returned percentage as an interpretive estimate.
QuillBot splits its detection service between an unpaid tier and a paid Premium subscription. The unpaid version allows quick classroom checks for individual paragraphs, while the Premium tier caters to high-volume document screening.
| Feature | Free Tier | Premium Tier |
|---|---|---|
| Word Limit Per Scan | Up to 1,200 words | No word limit |
| Daily Scan Allowance | Up to 6 scans per day | Unlimited scans |
| Explainer Cards | 1 explainer card | Full explainers |
| Reports | Not listed for Free | Downloadable and shareable reports |
The free tier works well for checking short passages, but its 6-scan daily ceiling limits routine grading workflows. A multi-page research report can run past the 1,200-word per-scan ceiling. Moving to Premium removes those volume walls and adds shareable reports that can be saved during an academic review. For broader institutional evaluations, teachers reviewing options for their departments can compare these features in the AI detector for teachers guide.
QuillBot's primary product is a Paraphraser, alongside a suite that includes an AI Humanizer, a Grammar Checker, and a Plagiarism Checker. That leads teachers to ask whether QuillBot's detector flags text run through QuillBot's own Paraphraser.
QuillBot's detector page says that heavily paraphrased or lightly AI-edited content is harder to classify for any automated checker on the market. QuillBot's detector may or may not flag that text, so the reliable way to know whether a student used QuillBot is the student disclosing it under the class AI policy. The AI humanizers guide covers QuillBot's AI Humanizer and similar products.
Because automated detection struggles with rephrased passages, educators must not treat a software scan as an investigative verdict. When evaluating student papers, teachers should look for corroborating authorship signals:
QuillBot advises users who rely on AI writing assistance to disclose it rather than revising to change a score. School departments should formalize these boundaries by embedding an AI syllabus statement into course overviews at the start of the semester. A written disclosure rule tells students which drafting help is allowed. If an educator suspects AI use, the guide on how to catch AI without a detector lists checks that do not depend on a score.
QuillBot's AI Detector needs at least 80 words of pasted text, so a single sentence or a short paragraph cannot be scanned.
QuillBot notes that texts of 300 words or more score more reliably than shorter passages. When running scans, avoid mixing disparate sections, such as an essay introduction pasted directly alongside a bibliographic reference list. QuillBot says formulaic human writing such as structured templates can score higher than expected, and a reference list follows a fixed template.
Teachers should also remember that other campus detection platforms report different metrics for the same pasted excerpt. For example, comparing a QuillBot score against a Turnitin AI score or scanning text through the Scribbr AI detector can yield different numbers, so no single number settles authorship. The guide on how teachers detect AI covers the classroom evidence that sits beside a score.
School administrators and academic integrity committees should not use the QuillBot AI detector as the primary basis for formal academic misconduct investigations. Because QuillBot explicitly cautions that its outputs are signals rather than verdicts, penalizing a student based solely on a high percentage score goes against QuillBot's own instruction. If an institution lacks secondary evidence, such as a blank revision history or an inability by the student to explain their own thesis, a high detection percentage remains purely circumstantial.
Students who find themselves falsely accused of using AI suffer when instructors treat detection percentages as definitive proof. If an instructor intends to cite software data in a disciplinary proceeding, the case needs corroborating evidence beyond the score itself. Teachers weighing QuillBot against Grammarly as a writing assistant can read the Grammarly vs QuillBot comparison.
QuillBot's AI Detector works as a screening aid and cannot settle a misconduct case. To establish a defensible assessment workflow, review your course writing expectations with students today and publish explicit guidelines on where automated drafting tools are permitted.
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QuillBot's AI detector provides an estimate rather than a definitive verdict. While QuillBot claims a 99 percent detection rate on the third-party RAID benchmark, QuillBot warns that no AI detector can provide 100 percent accuracy. Heavily paraphrased passages and formulaic human writing can produce misleading scores.
Yes, QuillBot offers a free version that scans up to 1,200 words per submission. Free users receive up to 6 scans per day and one explainer card per scan. A paid Premium plan removes the word cap and daily scan limits and adds full explainer cards and downloadable reports.
Not reliably from a score. QuillBot's detector may or may not flag text run through QuillBot's Paraphraser, and QuillBot says heavily paraphrased or lightly AI-edited text is harder for any checker to detect. The reliable route is a class AI policy that asks students to disclose QuillBot use, backed by drafts and a conversation about the writing.
In QuillBot's detector, 'AI-refined' identifies text that appears to be written primarily by a human but modified using AI assistance. This category separates light algorithmic editing or sentence polish from text that a machine generated entirely from scratch.
QuillBot's detector requires an input of at least 80 words to generate an analysis. However, QuillBot notes that scans containing 300 words or more score more reliably.