What you're looking for when you suspect AI wrote something

AI-written text has recognizable patterns: it tends to be unusually smooth and formal, avoids taking a real position, repeats the same sentence structures, and often includes phrases that sound like they came from a template. The most reliable way to catch it is to read for voice — does this sound like a real person with a point of view, or does it sound like something assembled from common phrases?

No single tool catches all AI writing, and no tool is right 100 percent of the time. The best approach combines reading the text yourself with checking it against a detector, then deciding based on what you actually see.

Key Takeaways

  • AI writing often uses the same sentence patterns repeatedly, avoids strong opinions, and includes generic phrases like "furthermore" or "perspectives vary."
  • Free detectors like GPTZero, Copyleaks, and OpenAI's own detector can flag AI text, but they make mistakes and miss some AI writing.
  • The most reliable signal is reading the text yourself — real writing has a voice, personality, and specific details that AI tends to smooth away.
  • AI detectors work better on longer pieces (500+ words) than on short paragraphs or social media posts.
  • Even if a detector says something is AI, you should read it yourself before deciding, because false positives happen regularly.

How to read text and spot AI patterns yourself

Start by reading the piece as if you're looking for a person behind it. Real writing has quirks: a writer repeats a favorite word, takes a side, uses short sentences when they're frustrated, or includes a specific detail that only someone who lived through it would know. AI writing is smoother and more cautious. It rarely says "I think" or "I disagree" — instead it says "some argue" or "perspectives vary."

Look for these specific patterns. Does every sentence follow the same structure — subject, verb, object, then a clause? Real writers vary their rhythm. Does the text use the same transition words over and over (furthermore, additionally, moreover)? AI does this constantly. Are there generic phrases that could fit anywhere (the world today, various perspectives, multiple factors)? Those are AI tells.

Check whether the writing takes a real position or just describes both sides without choosing. AI tends toward neutrality because it's trained to avoid offending anyone. A real person writing about something they care about usually has an opinion. If the piece is supposed to be advice or analysis but reads like a Wikipedia summary, that's a sign.

Look for specific details and examples. AI can invent them, but it often doesn't — it stays general. If an article about restaurants never names a single dish, or a piece about fixing a car never mentions an actual part, that's suspicious.

Using free AI detection tools

GPTZero is one of the most widely used free detectors. Paste your text into the box on their website, and it gives you a score for how likely the text is to be AI-generated. It also highlights sections it thinks are AI-written. The tool works better on longer pieces and sometimes flags human writing as AI if it's very formal or technical.

Copyleaks offers a free detector that works similarly — you paste text and get a percentage score. It also checks for plagiarism at the same time, which can be useful if you're checking whether someone copied something. Like GPTZero, it has a higher error rate on short texts.

OpenAI's own detector is available free on their website. Since OpenAI makes ChatGPT, you might expect it to be the most accurate at catching ChatGPT specifically. It's reasonably good, but it also makes mistakes and sometimes misses AI text.

None of these tools are perfect. They all have false positives — they flag human writing as AI — and false negatives, where they miss AI writing entirely. They work better on longer pieces (500 words or more) than on short paragraphs. If a detector says something is AI but the text reads like a real person wrote it, trust your reading.

What makes AI writing easier to spot in some situations

AI writing is easiest to catch when the topic requires specific knowledge or personal experience. If someone is writing about their own job, their own family, or something they actually did, real details usually show up. AI can fake details, but it often doesn't bother — it stays general instead. A real mechanic writing about fixing a transmission will mention actual tools and steps. AI writing about the same topic might describe the process correctly but without the small frustrations or tricks that a real mechanic would mention.

AI writing is also easier to spot when it's supposed to have a voice. A company's customer service email should sound like it came from a person. A social media post from a real account should have personality. When the writing is supposed to be neutral and informational — like a Wikipedia article or a technical manual — AI and human writing look more similar, and detectors have a harder time.

Short texts are harder to evaluate than long ones. A single paragraph or a few sentences don't give you enough pattern to recognize, and detectors need more material to work with. If you're checking a tweet or a short comment, reading it yourself is more reliable than running it through a tool.

Why detectors make mistakes

AI detectors work by looking for statistical patterns — they measure things like word choice, sentence length, and how predictable the next word is. The problem is that human writing can have the same patterns. A formal academic paper might look like AI because it uses long sentences and technical language. A very short text might look like AI just because there's not enough material to analyze.

Detectors also struggle because AI writing is getting better. Newer models like GPT-4 produce text that's harder to distinguish from human writing than older models did. A detector trained on ChatGPT 3.5 might not catch text from a newer system. And detectors trained on one AI system sometimes miss text from a different one.

The other direction matters too: detectors sometimes flag human writing as AI. If someone writes in a very formal style, or if English is not their first language and they write carefully, a detector might flag it incorrectly. This is why you should never use a detector alone to decide whether something is AI.

When you should check for AI writing

Check for AI writing when someone is claiming to have written something themselves and you have reason to doubt it. If a student submits an essay that sounds nothing like their usual writing, or if a freelancer's work suddenly becomes much more polished, it's worth checking. If you're reading something online and the voice seems off or the details seem suspiciously generic, checking is reasonable.

You might also check if you're trying to understand whether a piece was AI-generated for your own information — maybe you're curious whether a news article was written by a human or an AI system, or whether a social media post was automated. In those cases, checking helps you understand what you're reading.

Don't check for AI writing as a way to catch someone in a lie without other evidence. A detector flag alone isn't proof. Use it as one piece of information alongside what you actually read and what you know about the person or source.

What to do if you find AI writing where it shouldn't be

If you find AI writing in a situation where it matters — a student assignment, a job application, a freelance article you paid for — the next step depends on the context. In a school setting, talk to the teacher or your institution's academic integrity office. They have policies for this and can guide you. If it's a work situation, talk to your manager or HR. If you paid someone for writing and got AI instead, that's a contract issue — you can ask for a refund or rewrite.

If you find AI writing in a public place like social media or a website, you can report it to the platform if their rules prohibit it. Many platforms have policies against AI-generated content presented as human-written, though enforcement varies. You can also just choose not to trust or share that content.

Frequently Asked Questions

Can AI detectors tell the difference between ChatGPT and other AI systems?

Most detectors can't reliably tell you which AI system wrote something — they can only guess whether it's AI or human. Some detectors claim to identify specific systems, but they're not very accurate. If you need to know which system was used, that's usually not something a detector can tell you.

What if I write very formally — will a detector think I'm AI?

Yes, it might. Formal writing, technical writing, and writing in a second language can all trigger false positives. This is why reading the text yourself matters more than the detector score. If the writing sounds like a real person and has specific details, it's probably human even if the detector disagrees.

Do AI detectors work on text from ChatGPT, Claude, and other systems?

They work better on some systems than others. Detectors tend to be better at catching ChatGPT because that's what they're trained on. Text from Claude, Gemini, or other systems might slip through more often. No detector catches everything from every system.

Is it illegal to use AI to write something and claim you wrote it?

It depends on the context. In school, it violates academic integrity policies. In a job where you're hired to write, it could be grounds for firing. In most other situations, there's no law against it, but there might be a contract violation or a terms-of-service violation depending on where you're posting. The consequences are usually social or professional, not legal.

Can I use an AI detector on my own writing to make sure it doesn't sound like AI?

You can, but it's not the most useful way to check. If you want your writing to sound human, the better approach is to read it yourself and ask whether it has a voice, specific details, and your actual opinion in it. If it does, it will sound human. Trying to game a detector is less reliable than just writing naturally.