AI Writing Detector: Identify AI-Assisted Academic Writing
The AI writing detector measures what makes human and AI writing statistically different — perplexity, burstiness, sentence rhythm — and scores every sentence from 25 (human) to 75 (AI). Results in 15 minutes · from $0.29/page.
What Separates Human Writing from AI Writing?
The differences are statistical, not just stylistic. Understanding them explains why the detector works.
Human Writing
- High perplexity — unexpected but meaningful word choices
- High burstiness — sentences vary greatly in length and complexity
- Natural minor errors and informal constructions
- Personal voice, genuine opinion, idiosyncratic phrasing
- Specific examples and concrete details
AI Writing
- Low perplexity — always chooses the statistically expected word
- Low burstiness — sentences are similar in length throughout
- Perfect grammar throughout — no natural slip-ups
- Comprehensive but impersonal — avoids taking genuine positions
- Generic examples — rarely cites specific data or sources unprompted
Detect AI Writing in 3 Steps
Upload Your Document
Submit your paper as .docx, .pdf, .txt, .odt or .rtf. Up to 50 MB and 999 pages. No registration required.
Writing Style Analysis
PlagAware analyses perplexity, burstiness and token probability for every sentence. These three metrics distinguish human writing patterns from AI writing patterns with high reliability.
Scored Report Delivered
Within 15 minutes, a colour-coded PDF arrives in your inbox. Each sentence is scored 25–75. AI-detected sentences are highlighted in red — you know exactly what to revise.
AI Writing Models Detected
The detector identifies writing from all major AI platforms used in academic settings.
ChatGPT & GPT-4
The most common AI writing assistant in academic use. Both GPT-3.5 and GPT-4 are detected at the sentence level.
Claude & Gemini
Anthropic Claude and Google Gemini produce fluent academic text that the detector identifies reliably.
Llama, Mistral & Others
Open-source models widely deployed in writing assistants. See our LLM detector for the full model list.
Reading Your AI Writing Detector Score
The score of 25 represents the statistical baseline of human writing. The score of 75 represents the statistical baseline of AI writing. Most human-written academic text scores between 25 and 40.
It is normal for some sentences in a genuinely human-written paper to score above 40 — formal academic language occasionally produces higher scores. What distinguishes AI-written content is a sustained pattern of high scores across many consecutive sentences.
- Score 25–35: Confident human writing
- Score 36–55: Formal or ambiguous writing
- Score 56–75: AI writing detected
- Results delivered in 15 minutes
Score distribution — 52 pages analysed
Recommendation: 11% AI sentences detected across 6 passages. Review highlighted sentences before submission.
AI Writing Detector Pricing
Pay per page. No subscription. Minimum order $0.90.
Plagiarism Scan
Source-based plagiarism check
- 70+ billion sources
- Results in 15 minutes
- PDF with source links
- PlagAware powered
Combo: Plagiarism + AI
Complete writing integrity check
- Plagiarism check included
- AI writing detection
- All major LLMs covered
- Best value per page
AI Scan
AI writing detection only
- Perplexity & burstiness analysis
- Score 25–75 per sentence
- Results in 15 minutes
- Email delivery
AI Writing Detector — Frequently Asked Questions
Human writing is characterised by high perplexity (unpredictable word choices), high burstiness (variable sentence length and complexity), natural minor errors, personal voice and genuine opinion. AI writing exhibits low perplexity (predictable word choices), low burstiness (uniform sentence structure), perfect grammar, and comprehensive but impersonal language.
The detector measures three key properties: perplexity (how statistically predictable each word choice is), burstiness (how much sentence length and complexity varies throughout the text), and token probability distributions (whether words were chosen from a high-probability distribution, as AI does). These are combined to produce a score from 25 (human) to 75 (AI).
The detector does not categorise "AI-assisted" versus "fully AI-generated" — it measures the AI-generation signal of each sentence individually. A sentence that was heavily edited by a human after being generated by AI may score lower than an unedited AI sentence. The sentence-level scores allow you to assess the degree of AI involvement across your document.
AI writing detection is a statistical analysis task, not a database comparison. The detection engine analyses each sentence's linguistic patterns mathematically, which is computationally fast. Most documents are fully processed within a few minutes. The 15-minute window includes processing time and email delivery.
You can submit documents of up to 999 pages or 50 MB per order. For very large documents, the analysis may take slightly longer than 15 minutes but will be delivered within 24 hours. There is no per-order page minimum beyond the minimum order value of $0.90.
Know Whether Your Academic Writing Reads as Human or AI
Upload your paper and get a sentence-level AI writing analysis in 15 minutes.
Use code plagiarism-scan10 for 10% off.