How to Check If Text Is AI-Generated (Free) — and What the Score Means

Before submitting, a lot of people want to check whether their work will be flagged as AI. This article explains how free AI detectors work, what the score means, and how much to trust it.

How AI detectors work

Free tools like GPTZero, ZeroGPT and others don't "read and understand" your content — they look at two statistical patterns:

• Perplexity — how predictable the text is (AI tends to be predictable)
• Burstiness — how varied the sentences are (humans mix short and long)

The full principle is in Perplexity and Burstiness explained.

What the score actually means

Most tools give a percentage — "X% likely AI." The important thing to understand:

• It's a probability estimate, not a verdict
• No tool is 100% accurate — they both miss AI and flag humans
• Accuracy is worse outside English, since most tools are trained on English data

Compare how strict each tool is in Which AI detector is most accurate?, and GPTZero specifically in Is GPTZero accurate?.

Where to check for free

There are several free tools (GPTZero, ZeroGPT, etc.), but two cautions:

1. They disagree — the same text can score very differently across tools. Use them as a rough guide, not a final answer.
2. Watch your privacy — some sites store the text you paste; don't paste anything confidential.

What to do if your own writing gets flagged

Don't panic — false positives are real, especially on very formal writing. To lower the chance of being flagged incorrectly, make the writing read more naturally:

• Vary sentence length
• Avoid repeating formal connectors
• Add your own perspective

See the full method in How to write so your work isn't flagged as AI. And if you used AI to draft and want it to read more smoothly, Manutwrite's AI Humanizer makes text read naturally.

Summary

You can check for AI for free, but the score is an estimate, not a verdict — and it's less accurate outside English. If your own writing gets flagged, make it read more naturally rather than panicking.

Note: Use AI tools responsibly and in line with your institution's policies.