How to Detect AI-Generated Text (7 Reliable Methods)
Learn how to tell if text was written by AI. We test GPTZero, Originality.ai, and other detectors — and share what actually works in 2026.
TL;DR
No AI detector is 100% accurate. GPTZero is the best free option for occasional use. Originality.ai ($30/mo) is worth it for publishers and educators who need bulk checking. Turnitin is the standard for academic use.
Why AI Detection Is Hard
AI models are trained to write like humans. The better the model, the harder detection becomes. Most detectors look for:
- Overly consistent sentence length
- Lack of personal anecdotes
- High “perplexity” patterns (too predictable)
- Burstiness (humans vary length more)
No single signal is definitive. Detectors work by probability, not certainty.
7 Methods to Detect AI Text
Method 1: Use GPTZero (Free)
- Go to gptzero.me
- Paste the text (up to 5,000 characters free)
- Click “Check”
- Review the score: “Human,” “Mixed,” or “AI”
- Yellow highlights = sentences flagged as likely AI
Accuracy: ~85% on unmodified AI text; drops significantly if text is edited.
Method 2: Use Originality.ai (Paid, More Reliable)
Best for content marketing teams and publishers.
- Create account → $30/mo for 2,000 credits
- Paste URL or text
- Get a score + sentence-level breakdown
- Also checks for plagiarism simultaneously
Method 3: Look for These AI Writing Patterns
Manually scan for:
- “Certainly!” / “Of course!” / “Absolutely!” — AI overuses these
- “It’s important to note that…” — classic AI filler
- “In conclusion, …” — AI loves formal transitions
- Perfect paragraph structure every time — humans are messier
- No typos or informal language — suspicious for casual writing
- Vague instead of specific — “many studies show” vs naming the study
Method 4: Ask Specific Questions About the Content
If you suspect AI content, ask the author:
- “What’s the source for this specific claim?”
- “What was your personal experience with X?”
- “Can you expand on [very specific detail]?”
AI content often can’t be defended with specifics.
Method 5: Check Writing History
- Google Docs revision history
- GitHub commit timestamps
- Article publish/edit timestamps
Pasted AI content often appears as a single paste event, not gradual typing.
Method 6: Run Through Multiple Detectors
No single tool is reliable. Cross-reference:
- GPTZero (free)
- Copyleaks (freemium)
- Writer.com AI detector (free)
- Sapling AI detector (free)
If 3+ detectors flag it, confidence increases.
Method 7: Ask the AI Itself
Paste the text into ChatGPT and ask: “Was this written by an AI?” AI models sometimes recognize their own patterns, though this isn’t reliable either.
Detector Comparison
| Tool | Price | Best For | Accuracy |
|---|---|---|---|
| GPTZero | Free / $10mo | Students, teachers | Good |
| Originality.ai | $30/mo | Publishers, SEO | Very Good |
| Turnitin | Institutional | Academia | Industry standard |
| Copyleaks | Free/Paid | Plagiarism+AI | Good |
| Writer.com | Free | Quick checks | Fair |
FAQ
Can AI detectors give false positives on human writing? Yes, especially for ESL writers, technical writing, or very formal styles. Never use a detector result as the sole basis for an accusation.
Can you fool AI detectors? Yes. Paraphrasing tools, mixing AI and human writing, or adding personal details significantly reduces detection rates. Detectors are a signal, not a verdict.
Is AI-generated content against the rules? Depends on context. Most academic institutions prohibit it without disclosure. Google doesn’t penalize AI content per se — but penalizes low-quality, unhelpful content regardless of origin.