Something Feels Off About This Writing. Here Is How to Check If It Is LLM-Generated

Say you're reviewing freelance submissions for a small publication. A draft lands in your inbox and something about it feels... smooth. Too smooth. Every sentence flows perfectly. No awkward phrasing. No personality. You start wondering: did a human actually write this, or did someone feed a prompt into ChatGPT and hit send?

That feeling is the starting point for most people who search "check if text is LLM generated." And if you've never done this before, the whole thing can seem technical. It doesn't have to be. Here's what's actually happening — and how to check.

What Does "LLM-Generated" Actually Mean?

LLM stands for Large Language Model. It's the technology behind tools like ChatGPT, Claude, and Gemini. When someone says text is "LLM-generated," they mean software produced it — not a person.

Think of it this way: an LLM is a very sophisticated autocomplete. It has processed enormous amounts of text and learned to predict what word typically comes next. The result is writing that is grammatically clean, logically structured, and statistically predictable. That predictability is exactly what AI detectors are designed to find.

How Do AI Text Detectors Actually Work?

AI detectors analyze patterns in text rather than reading it for meaning. There are two main signals they look for:

• Perplexity: How surprising the word choices are. Human writers often pick unexpected phrases, shift tone mid-paragraph, or build sentences in ways that feel slightly unpredictable. AI tends to reach for the statistically safe option — which gives it low perplexity.
• Burstiness: How much sentence length varies. Real writing tends to mix short punchy lines with longer, winding ones. AI often produces sentences that are more uniform — similar in length, similar in structure, almost metronomic.

Getting a handle on how AI detectors work at a mechanical level helps you interpret results more accurately, rather than treating the output as a simple pass/fail verdict.

How to Run a Check: A Simple Starting Point

Running a check is straightforward. WriteMask's free AI detector lets you paste any block of text and get an instant analysis — no account required. The tool scans the phrasing patterns and gives you a readout of how likely the text is to have come from a language model.

A few practical tips before you start:

• Use a substantial sample. A sentence or two doesn't give the detector enough to work with. A few full paragraphs produces a more reliable result.
• Check sections separately if the document is long. Sometimes only part of a piece is AI-generated. Running the whole thing as one block can dilute the signal from the flagged sections.
• Don't treat the result as the final word. More on that below.

What Do the Results Actually Mean?

Most detectors return a likelihood score — something like "likely AI-generated" or "likely human." These are probability estimates, not certainties.

A result flagging text as likely AI means the phrasing patterns closely resemble how language models typically write. It doesn't prove that an AI wrote it. And a "likely human" result doesn't prove the opposite either. It just means the detector didn't find the usual statistical fingerprints.

This is why AI detection false positives are a genuine problem. Some humans naturally write in clear, structured, repetitive prose — especially people writing in a second language, or those following a rigid template. Detectors can flag their work incorrectly.

What Should You Do With the Results?

Think of a detector score as a signal to investigate, not a verdict to act on. If a check flags text as likely AI-generated, that's a prompt to look more closely — not to immediately confront someone or discard the work.

A reasonable process:

• Run the check. Note which sections score as likely AI.
• Read those sections yourself. Does this sound like the person's other writing? Is there a personal example, an unusual word choice, a digression that feels genuinely human?
• Compare with other writing samples from the same person if you have them.
• Ask a clarifying question. In professional or academic contexts, a brief follow-up conversation often reveals more than any detector score.

If you're on the receiving end of this — you used AI as a drafting tool and are now worried about being flagged — proving your writing is human is a different process with its own steps worth knowing.

Train Your Own Eye, Too

One underrated approach: try the AI or Human? game. It shows you real text samples and asks you to guess which were written by a person. After a few rounds, you start noticing the tell-tale signs yourself — the rhythm that never stumbles, the transitions that always land perfectly, the total absence of anything that sounds like an actual voice.

That intuition is worth building. Tools give you a starting point. Your judgment makes the final call.

A Note If You're on the Other Side

If you write using AI tools and want to make sure your final output reads as genuinely human, WriteMask is built for exactly that. It's the platform side of the same coin — designed to help writers produce content that passes major detectors while preserving meaning and quality, with a 93% pass rate against leading detection tools.

Whichever side of this you're on, the most important thing is understanding what these tools are actually measuring. They're pattern-matchers, not mind-readers. Use them accordingly.